21212790 has 32 divisors (see below), whose sum is σ = 51287040. Its totient is φ = 5614944.

The previous prime is 21212777. The next prime is 21212809. The reversal of 21212790 is 9721212.

It is a self number, because there is not a number n which added to its sum of digits gives 21212790.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1627 + ... + 6713.

It is an arithmetic number, because the mean of its divisors is an integer number (1602720).

Almost surely, 2^21212790 is an apocalyptic number.

21212790 is an abundant number, since it is smaller than the sum of its proper divisors (30074250).

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

21212790 is a wasteful number, since it uses less digits than its factorization.

21212790 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5236.

The product of its (nonzero) digits is 504, while the sum is 24.

The square root of 21212790 is about 4605.7344691156. The cubic root of 21212790 is about 276.8211472561.

The spelling of 21212790 in words is "twenty-one million, two hundred twelve thousand, seven hundred ninety".