21930911 has 4 divisors (see below), whose sum is σ = 21940800. Its totient is φ = 21921024.

The previous prime is 21930893. The next prime is 21930913. The reversal of 21930911 is 11903912.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21930911 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21930913) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 95 + ... + 6623.

It is an arithmetic number, because the mean of its divisors is an integer number (5485200).

Almost surely, 2^21930911 is an apocalyptic number.

21930911 is a deficient number, since it is larger than the sum of its proper divisors (9889).

21930911 is an equidigital number, since it uses as much as digits as its factorization.

21930911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9888.

The product of its (nonzero) digits is 486, while the sum is 26.

The square root of 21930911 is about 4683.0450563709. The cubic root of 21930911 is about 279.9103071560.

The spelling of 21930911 in words is "twenty-one million, nine hundred thirty thousand, nine hundred eleven".