691926561 has 6 divisors (see below), whose sum is σ = 999449490. Its totient is φ = 461284368.

The previous prime is 691926539. The next prime is 691926569. The reversal of 691926561 is 165629196.

It is a happy number.

691926561 is a `hidden beast` number, since 69 + 1 + 9 + 26 + 561 = 666.

It can be written as a sum of positive squares in only one way, i.e., 674960400 + 16966161 = 25980^2 + 4119^2 .

It is not a de Polignac number, because 691926561 - 2¹³ = 691918369 is a prime.

It is not an unprimeable number, because it can be changed into a prime (691926569) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 38440356 + ... + 38440373.

It is an arithmetic number, because the mean of its divisors is an integer number (166574915).

Almost surely, 2^691926561 is an apocalyptic number.

It is an amenable number.

691926561 is a deficient number, since it is larger than the sum of its proper divisors (307522929).

691926561 is a wasteful number, since it uses less digits than its factorization.

691926561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76880735 (or 76880732 counting only the distinct ones).

The product of its digits is 174960, while the sum is 45.

The square root of 691926561 is about 26304.4969729512. The cubic root of 691926561 is about 884.4772513736.

The spelling of 691926561 in words is "six hundred ninety-one million, nine hundred twenty-six thousand, five hundred sixty-one".