81571601 has 4 divisors (see below), whose sum is σ = 81630192. Its totient is φ = 81513012.

The previous prime is 81571597. The next prime is 81571603. The reversal of 81571601 is 10617518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 10617518 = 2 ⋅5308759.

It is a cyclic number.

It is not a de Polignac number, because 81571601 - 2² = 81571597 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81571603) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27155 + ... + 30008.

It is an arithmetic number, because the mean of its divisors is an integer number (20407548).

Almost surely, 2^81571601 is an apocalyptic number.

It is an amenable number.

81571601 is a deficient number, since it is larger than the sum of its proper divisors (58591).

81571601 is a wasteful number, since it uses less digits than its factorization.

81571601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58590.

The product of its (nonzero) digits is 1680, while the sum is 29.

The square root of 81571601 is about 9031.6997846474. The cubic root of 81571601 is about 433.6902534067.

The spelling of 81571601 in words is "eighty-one million, five hundred seventy-one thousand, six hundred one".