21591712 has 12 divisors (see below), whose sum is σ = 42508746. Its totient is φ = 10795840.

The previous prime is 21591709. The next prime is 21591737. The reversal of 21591712 is 21719512.

It can be written as a sum of positive squares in only one way, i.e., 19044496 + 2547216 = 4364^2 + 1596^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 337339 + ... + 337402.

Almost surely, 2^21591712 is an apocalyptic number.

It is an amenable number.

21591712 is a deficient number, since it is larger than the sum of its proper divisors (20917034).

21591712 is an equidigital number, since it uses as much as digits as its factorization.

21591712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 674751 (or 674743 counting only the distinct ones).

The product of its digits is 1260, while the sum is 28.

The square root of 21591712 is about 4646.6882830678. The cubic root of 21591712 is about 278.4597055634.

The spelling of 21591712 in words is "twenty-one million, five hundred ninety-one thousand, seven hundred twelve".