691564040 has 96 divisors (see below), whose sum is σ = 1630487880. Its totient is φ = 263927808.

The previous prime is 691564039. The next prime is 691564057. The reversal of 691564040 is 40465196.

It can be written as a sum of positive squares in 12 ways, for example, as 520843684 + 170720356 = 22822^2 + 13066^2 .

It is a super-2 number, since 2×691564040² = 956521642842243200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3997394 + ... + 3997566.

Almost surely, 2^691564040 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 691564040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (815243940).

691564040 is an abundant number, since it is smaller than the sum of its proper divisors (938923840).

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

691564040 is a wasteful number, since it uses less digits than its factorization.

691564040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331 (or 290 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 691564040 is about 26297.6052141635. The cubic root of 691564040 is about 884.3227563689.

The spelling of 691564040 in words is "six hundred ninety-one million, five hundred sixty-four thousand, forty".