857221531 has 4 divisors (see below), whose sum is σ = 858607000. Its totient is φ = 855836064.

The previous prime is 857221511. The next prime is 857221543. The reversal of 857221531 is 135122758.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 857221531 - 2¹¹ = 857219483 is a prime.

It is a super-2 number, since 2×857221531² = 1469657506419967922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (857221511) 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, 691806 + ... + 693043.

It is an arithmetic number, because the mean of its divisors is an integer number (214651750).

Almost surely, 2^857221531 is an apocalyptic number.

857221531 is a deficient number, since it is larger than the sum of its proper divisors (1385469).

857221531 is a wasteful number, since it uses less digits than its factorization.

857221531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1385468.

The product of its digits is 16800, while the sum is 34.

The square root of 857221531 is about 29278.3457695273. The cubic root of 857221531 is about 949.9433136998.

It can be divided in two parts, 8572 and 21531, that added together give a palindrome (30103).

The spelling of 857221531 in words is "eight hundred fifty-seven million, two hundred twenty-one thousand, five hundred thirty-one".