21091392 has 84 divisors (see below), whose sum is σ = 69104256. Its totient is φ = 6024960.

The previous prime is 21091361. The next prime is 21091409. The reversal of 21091392 is 29319012.

It is a tau number, because it is divible by the number of its divisors (84).

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, 1417 + ... + 6647.

Almost surely, 2^21091392 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 21091392, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34552128).

21091392 is an abundant number, since it is smaller than the sum of its proper divisors (48012864).

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

21091392 is a wasteful number, since it uses less digits than its factorization.

21091392 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5256 (or 5243 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 21091392 is about 4592.5365540189. The cubic root of 21091392 is about 276.2920663743.

The spelling of 21091392 in words is "twenty-one million, ninety-one thousand, three hundred ninety-two".