19961820 has 36 divisors (see below), whose sum is σ = 60551400. Its totient is φ = 5323104.

The previous prime is 19961783. The next prime is 19961827. The reversal of 19961820 is 2816991.

19961820 is a `hidden beast` number, since 19 + 9 + 618 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19961827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 55270 + ... + 55629.

Almost surely, 2^19961820 is an apocalyptic number.

19961820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19961820 is an abundant number, since it is smaller than the sum of its proper divisors (40589580).

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

19961820 is a wasteful number, since it uses less digits than its factorization.

19961820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110914 (or 110909 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 19961820 is about 4467.8652620687. The cubic root of 19961820 is about 271.2689241895.

The spelling of 19961820 in words is "nineteen million, nine hundred sixty-one thousand, eight hundred twenty".