21402812 has 24 divisors (see below), whose sum is σ = 38937360. Its totient is φ = 10281600.

The previous prime is 21402763. The next prime is 21402817. The reversal of 21402812 is 21820412.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21402817) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35312 + ... + 35912.

It is an arithmetic number, because the mean of its divisors is an integer number (1622390).

Almost surely, 2^21402812 is an apocalyptic number.

It is an amenable number.

21402812 is a deficient number, since it is larger than the sum of its proper divisors (17534548).

21402812 is a wasteful number, since it uses less digits than its factorization.

21402812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 941 (or 939 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 21402812 is about 4626.3173259084. The cubic root of 21402812 is about 277.6452698251.

The spelling of 21402812 in words is "twenty-one million, four hundred two thousand, eight hundred twelve".