21646916 has 12 divisors (see below), whose sum is σ = 40110588. Its totient is φ = 10186752.

The previous prime is 21646913. The next prime is 21646921. The reversal of 21646916 is 61964612.

It can be written as a sum of positive squares in 2 ways, for example, as 9424900 + 12222016 = 3070^2 + 3496^2 .

It is a super-2 number, since 2×21646916² = 937177944622112, which contains 22 as substring.

It is a hoax number, since the sum of its digits (35) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21646913) 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, 159101 + ... + 159236.

It is an arithmetic number, because the mean of its divisors is an integer number (3342549).

Almost surely, 2^21646916 is an apocalyptic number.

It is an amenable number.

21646916 is a deficient number, since it is larger than the sum of its proper divisors (18463672).

21646916 is a wasteful number, since it uses less digits than its factorization.

21646916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 318358 (or 318356 counting only the distinct ones).

The product of its digits is 15552, while the sum is 35.

The square root of 21646916 is about 4652.6246356223. The cubic root of 21646916 is about 278.6968182643.

The spelling of 21646916 in words is "twenty-one million, six hundred forty-six thousand, nine hundred sixteen".