81570657 has 32 divisors (see below), whose sum is σ = 128314368. Its totient is φ = 45130176.

The previous prime is 81570637. The next prime is 81570677. The reversal of 81570657 is 75607518.

It is an interprime number because it is at equal distance from previous prime (81570637) and next prime (81570677).

It is not a de Polignac number, because 81570657 - 2²³ = 73182049 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81570637) 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, 91938 + ... + 92820.

It is an arithmetic number, because the mean of its divisors is an integer number (4009824).

Almost surely, 2^81570657 is an apocalyptic number.

It is an amenable number.

81570657 is a deficient number, since it is larger than the sum of its proper divisors (46743711).

81570657 is a wasteful number, since it uses less digits than its factorization.

81570657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1029.

The product of its (nonzero) digits is 58800, while the sum is 39.

The square root of 81570657 is about 9031.6475241232. The cubic root of 81570657 is about 433.6885804176.

The spelling of 81570657 in words is "eighty-one million, five hundred seventy thousand, six hundred fifty-seven".