21921560 has 16 divisors (see below), whose sum is σ = 49323600. Its totient is φ = 8768608.

The previous prime is 21921547. The next prime is 21921563. The reversal of 21921560 is 6512912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21921563) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 273980 + ... + 274059.

It is an arithmetic number, because the mean of its divisors is an integer number (3082725).

Almost surely, 2^21921560 is an apocalyptic number.

21921560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21921560 is an abundant number, since it is smaller than the sum of its proper divisors (27402040).

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

21921560 is a wasteful number, since it uses less digits than its factorization.

21921560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 548050 (or 548046 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 21921560 is about 4682.0465610671. The cubic root of 21921560 is about 279.8705183638.

The spelling of 21921560 in words is "twenty-one million, nine hundred twenty-one thousand, five hundred sixty".