21912730 has 32 divisors (see below), whose sum is σ = 45722880. Its totient is φ = 7405440.

The previous prime is 21912727. The next prime is 21912733. The reversal of 21912730 is 3721912.

It is an interprime number because it is at equal distance from previous prime (21912727) and next prime (21912733).

It is a junction number, because it is equal to n+sod(n) for n = 21912695 and 21912704.

It is not an unprimeable number, because it can be changed into a prime (21912733) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2766 + ... + 7174.

It is an arithmetic number, because the mean of its divisors is an integer number (1428840).

Almost surely, 2^21912730 is an apocalyptic number.

21912730 is an abundant number, since it is smaller than the sum of its proper divisors (23810150).

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

21912730 is a wasteful number, since it uses less digits than its factorization.

21912730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4494.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 21912730 is about 4681.1035023806. The cubic root of 21912730 is about 279.8329360542.

The spelling of 21912730 in words is "twenty-one million, nine hundred twelve thousand, seven hundred thirty".