81697707 has 64 divisors (see below), whose sum is σ = 152785920. Its totient is φ = 41990400.

The previous prime is 81697697. The next prime is 81697709. The reversal of 81697707 is 70779618.

It is a happy number.

It is not a de Polignac number, because 81697707 - 2⁴ = 81697691 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81697709) 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 63 ways as a sum of consecutive naturals, for example, 100332 + ... + 101142.

It is an arithmetic number, because the mean of its divisors is an integer number (2387280).

Almost surely, 2^81697707 is an apocalyptic number.

81697707 is a deficient number, since it is larger than the sum of its proper divisors (71088213).

81697707 is a wasteful number, since it uses less digits than its factorization.

81697707 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 881 (or 875 counting only the distinct ones).

The product of its (nonzero) digits is 148176, while the sum is 45.

The square root of 81697707 is about 9038.6783879061. The cubic root of 81697707 is about 433.9136268331.

It can be divided in two parts, 8169 and 7707, that added together give a square (15876 = 126²).

The spelling of 81697707 in words is "eighty-one million, six hundred ninety-seven thousand, seven hundred seven".