691002081 has 36 divisors (see below), whose sum is σ = 1253843136. Its totient is φ = 358958160.

The previous prime is 691002061. The next prime is 691002139. The reversal of 691002081 is 180200196.

It is not a de Polignac number, because 691002081 - 2⁵ = 691002049 is a prime.

It is a super-2 number, since 2×691002081² = 954967751892661122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (691002031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 37701 + ... + 52946.

It is an arithmetic number, because the mean of its divisors is an integer number (34828976).

Almost surely, 2^691002081 is an apocalyptic number.

It is an amenable number.

691002081 is a deficient number, since it is larger than the sum of its proper divisors (562841055).

691002081 is a wasteful number, since it uses less digits than its factorization.

691002081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90682 (or 90668 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 691002081 is about 26286.9184386455. The cubic root of 691002081 is about 884.0831604335.

The spelling of 691002081 in words is "six hundred ninety-one million, two thousand, eighty-one".