21920916 has 12 divisors (see below), whose sum is σ = 51148832. Its totient is φ = 7306968.

The previous prime is 21920911. The next prime is 21920917. The reversal of 21920916 is 61902912.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21920911) 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 3 ways as a sum of consecutive naturals, for example, 913360 + ... + 913383.

Almost surely, 2^21920916 is an apocalyptic number.

It is an amenable number.

21920916 is an abundant number, since it is smaller than the sum of its proper divisors (29227916).

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

21920916 is a wasteful number, since it uses less digits than its factorization.

21920916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1826750 (or 1826748 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 30.

The square root of 21920916 is about 4681.9777872177. The cubic root of 21920916 is about 279.8677777075.

The spelling of 21920916 in words is "twenty-one million, nine hundred twenty thousand, nine hundred sixteen".