21257331 has 8 divisors (see below), whose sum is σ = 28550544. Its totient is φ = 14067840.

The previous prime is 21257323. The next prime is 21257347. The reversal of 21257331 is 13375212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21257331 - 2³ = 21257323 is a prime.

It is a super-2 number, since 2×21257331² = 903748242487122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21250331) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25450 + ... + 26271.

It is an arithmetic number, because the mean of its divisors is an integer number (3568818).

Almost surely, 2^21257331 is an apocalyptic number.

21257331 is a deficient number, since it is larger than the sum of its proper divisors (7293213).

21257331 is a wasteful number, since it uses less digits than its factorization.

21257331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51861.

The product of its digits is 1260, while the sum is 24.

The square root of 21257331 is about 4610.5673186713. The cubic root of 21257331 is about 277.0147611243.

The spelling of 21257331 in words is "twenty-one million, two hundred fifty-seven thousand, three hundred thirty-one".