21257712 has 60 divisors (see below), whose sum is σ = 67994160. Its totient is φ = 6073344.

The previous prime is 21257699. The next prime is 21257729. The reversal of 21257712 is 21775212.

It is a zygodrome in base 3.

It is a congruent number.

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, 9537 + ... + 11552.

It is an arithmetic number, because the mean of its divisors is an integer number (1133236).

Almost surely, 2^21257712 is an apocalyptic number.

It is an amenable number.

21257712 is an abundant number, since it is smaller than the sum of its proper divisors (46736448).

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

21257712 is a wasteful number, since it uses less digits than its factorization.

21257712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21110 (or 21101 counting only the distinct ones).

The product of its digits is 1960, while the sum is 27.

The square root of 21257712 is about 4610.6086366119. The cubic root of 21257712 is about 277.0164161141.

The spelling of 21257712 in words is "twenty-one million, two hundred fifty-seven thousand, seven hundred twelve".