391981279770 has 144 divisors (see below), whose sum is σ = 1039050543960. Its totient is φ = 102517747200.

The previous prime is 391981279769. The next prime is 391981279777. The reversal of 391981279770 is 77972189193.

It is a happy number.

391981279770 is a `hidden beast` number, since 391 + 98 + 1 + 2 + 7 + 97 + 70 = 666.

It can be written as a sum of positive squares in 12 ways, for example, as 334036605681 + 57944674089 = 577959^2 + 240717^2 .

It is a super-2 number, since 2×391981279770² (a number of 24 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 391981279698 and 391981279707.

It is not an unprimeable number, because it can be changed into a prime (391981279777) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 100069852 + ... + 100073768.

Almost surely, 2^391981279770 is an apocalyptic number.

391981279770 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 391981279770, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (519525271980).

391981279770 is an abundant number, since it is smaller than the sum of its proper divisors (647069264190).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

391981279770 is a wasteful number, since it uses less digits than its factorization.

391981279770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4241 (or 4137 counting only the distinct ones).

The product of its (nonzero) digits is 12002256, while the sum is 63.

The spelling of 391981279770 in words is "three hundred ninety-one billion, nine hundred eighty-one million, two hundred seventy-nine thousand, seven hundred seventy".