661172949 has 10 divisors (see below), whose sum is σ = 987678230. Its totient is φ = 440781912.

The previous prime is 661172947. The next prime is 661172969. The reversal of 661172949 is 949271166.

661172949 is a `hidden beast` number, since 6 + 611 + 7 + 29 + 4 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 357890724 + 303282225 = 18918^2 + 17415^2 .

It is not a de Polignac number, because 661172949 - 2¹ = 661172947 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661172947) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 4081234 + ... + 4081395.

It is an arithmetic number, because the mean of its divisors is an integer number (98767823).

Almost surely, 2^661172949 is an apocalyptic number.

It is an amenable number.

661172949 is a deficient number, since it is larger than the sum of its proper divisors (326505281).

661172949 is an equidigital number, since it uses as much as digits as its factorization.

661172949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8162641 (or 8162632 counting only the distinct ones).

The product of its digits is 163296, while the sum is 45.

The square root of 661172949 is about 25713.2835126127. The cubic root of 661172949 is about 871.1742408088.

The spelling of 661172949 in words is "six hundred sixty-one million, one hundred seventy-two thousand, nine hundred forty-nine".