851572661 has 4 divisors (see below), whose sum is σ = 859531392. Its totient is φ = 843613932.

The previous prime is 851572643. The next prime is 851572663. The reversal of 851572661 is 166275158.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-851572661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (851572663) 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, 3979205 + ... + 3979418.

It is an arithmetic number, because the mean of its divisors is an integer number (214882848).

Almost surely, 2^851572661 is an apocalyptic number.

It is an amenable number.

851572661 is a deficient number, since it is larger than the sum of its proper divisors (7958731).

851572661 is a wasteful number, since it uses less digits than its factorization.

851572661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7958730.

The product of its digits is 100800, while the sum is 41.

The square root of 851572661 is about 29181.7179240702. The cubic root of 851572661 is about 947.8520858112.

The spelling of 851572661 in words is "eight hundred fifty-one million, five hundred seventy-two thousand, six hundred sixty-one".