285981921 has 15 divisors (see below), whose sum is σ = 427435041. Its totient is φ = 190553148.

The previous prime is 285981893. The next prime is 285981947. The reversal of 285981921 is 129189582.

The square root of 285981921 is 16911.

It is a perfect power (a square), and thus also a powerful number.

285981921 is a `hidden beast` number, since 28 + 598 + 19 + 21 = 666.

It is not a de Polignac number, because 285981921 - 2¹⁷ = 285850849 is a prime.

It is not an unprimeable number, because it can be changed into a prime (285981961) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 151260 + ... + 153138.

Almost surely, 2^285981921 is an apocalyptic number.

285981921 is the 16911-st square number.

285981921 is the 8456-th centered octagonal number.

It is an amenable number.

285981921 is a deficient number, since it is larger than the sum of its proper divisors (141453120).

285981921 is an frugal number, since it uses more digits than its factorization.

285981921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3770 (or 1882 counting only the distinct ones).

The product of its digits is 103680, while the sum is 45.

The cubic root of 285981921 is about 658.8393444009.

The spelling of 285981921 in words is "two hundred eighty-five million, nine hundred eighty-one thousand, nine hundred twenty-one".