21257376 has 72 divisors (see below), whose sum is σ = 64925280. Its totient is φ = 6072192.

The previous prime is 21257347. The next prime is 21257407. The reversal of 21257376 is 67375212.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2445 + ... + 6963.

It is an arithmetic number, because the mean of its divisors is an integer number (901740).

Almost surely, 2^21257376 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21257376, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32462640).

21257376 is an abundant number, since it is smaller than the sum of its proper divisors (43667904).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21257376 is a wasteful number, since it uses less digits than its factorization.

21257376 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4546 (or 4531 counting only the distinct ones).

The product of its digits is 17640, while the sum is 33.

The square root of 21257376 is about 4610.5721987623. The cubic root of 21257376 is about 277.0149565966.

The spelling of 21257376 in words is "twenty-one million, two hundred fifty-seven thousand, three hundred seventy-six".