21930786 has 24 divisors (see below), whose sum is σ = 49156380. Its totient is φ = 7058016.

The previous prime is 21930743. The next prime is 21930791. The reversal of 21930786 is 68703912.

It can be written as a sum of positive squares in 2 ways, for example, as 21483225 + 447561 = 4635^2 + 669^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21930786.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20485 + ... + 21528.

Almost surely, 2^21930786 is an apocalyptic number.

21930786 is an abundant number, since it is smaller than the sum of its proper divisors (27225594).

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

21930786 is a wasteful number, since it uses less digits than its factorization.

21930786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42050 (or 42047 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21930786 is about 4683.0317103347. The cubic root of 21930786 is about 279.9097753517.

The spelling of 21930786 in words is "twenty-one million, nine hundred thirty thousand, seven hundred eighty-six".