21421560 has 32 divisors (see below), whose sum is σ = 64265040. Its totient is φ = 5712384.

The previous prime is 21421559. The next prime is 21421597. The reversal of 21421560 is 6512412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 89137 + ... + 89376.

Almost surely, 2^21421560 is an apocalyptic number.

21421560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21421560 is an abundant number, since it is smaller than the sum of its proper divisors (42843480).

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

21421560 is a wasteful number, since it uses less digits than its factorization.

21421560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178527 (or 178523 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21421560 is about 4628.3431160622. The cubic root of 21421560 is about 277.7263148514.

Adding to 21421560 its reverse (6512412), we get a palindrome (27933972).

The spelling of 21421560 in words is "twenty-one million, four hundred twenty-one thousand, five hundred sixty".