21277257 has 16 divisors (see below), whose sum is σ = 29581632. Its totient is φ = 13590720.

The previous prime is 21277247. The next prime is 21277261. The reversal of 21277257 is 75277212.

It is not a de Polignac number, because 21277257 - 2¹¹ = 21275209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21277247) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6007 + ... + 8867.

It is an arithmetic number, because the mean of its divisors is an integer number (1848852).

Almost surely, 2^21277257 is an apocalyptic number.

It is an amenable number.

21277257 is a deficient number, since it is larger than the sum of its proper divisors (8304375).

21277257 is a wasteful number, since it uses less digits than its factorization.

21277257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2968.

The product of its digits is 13720, while the sum is 33.

The square root of 21277257 is about 4612.7277179560. The cubic root of 21277257 is about 277.1012892705.

The spelling of 21277257 in words is "twenty-one million, two hundred seventy-seven thousand, two hundred fifty-seven".