81697605 has 32 divisors (see below), whose sum is σ = 144955008. Its totient is φ = 38956800.

The previous prime is 81697601. The next prime is 81697607. The reversal of 81697605 is 50679618.

It is not a de Polignac number, because 81697605 - 2² = 81697601 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81697601) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6007 + ... + 14123.

It is an arithmetic number, because the mean of its divisors is an integer number (4529844).

Almost surely, 2^81697605 is an apocalyptic number.

It is an amenable number.

81697605 is a deficient number, since it is larger than the sum of its proper divisors (63257403).

81697605 is a wasteful number, since it uses less digits than its factorization.

81697605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8197.

The product of its (nonzero) digits is 90720, while the sum is 42.

The square root of 81697605 is about 9038.6727454865. The cubic root of 81697605 is about 433.9134462519.

The spelling of 81697605 in words is "eighty-one million, six hundred ninety-seven thousand, six hundred five".