21212056 has 32 divisors (see below), whose sum is σ = 44334000. Its totient is φ = 9455616.

The previous prime is 21212033. The next prime is 21212071. The reversal of 21212056 is 65021212.

It is a Harshad number since it is a multiple of its sum of digits (19).

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, 1521 + ... + 6688.

Almost surely, 2^21212056 is an apocalyptic number.

It is an amenable number.

21212056 is an abundant number, since it is smaller than the sum of its proper divisors (23121944).

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

21212056 is a wasteful number, since it uses less digits than its factorization.

21212056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8251 (or 8247 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 21212056 is about 4605.6547851527. The cubic root of 21212056 is about 276.8179543857.

Adding to 21212056 its reverse (65021212), we get a palindrome (86233268).

The spelling of 21212056 in words is "twenty-one million, two hundred twelve thousand, fifty-six".