21945916 has 6 divisors (see below), whose sum is σ = 38405360. Its totient is φ = 10972956.

The previous prime is 21945907. The next prime is 21945943. The reversal of 21945916 is 61954912.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2743236 + ... + 2743243.

Almost surely, 2^21945916 is an apocalyptic number.

It is an amenable number.

21945916 is a deficient number, since it is larger than the sum of its proper divisors (16459444).

21945916 is a wasteful number, since it uses less digits than its factorization.

21945916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5486483 (or 5486481 counting only the distinct ones).

The product of its digits is 19440, while the sum is 37.

The square root of 21945916 is about 4684.6468383433. The cubic root of 21945916 is about 279.9741302630.

The spelling of 21945916 in words is "twenty-one million, nine hundred forty-five thousand, nine hundred sixteen".