20721964 has 12 divisors (see below), whose sum is σ = 36300600. Its totient is φ = 10350368.

The previous prime is 20721949. The next prime is 20721983. The reversal of 20721964 is 46912702.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3147 + ... + 7165.

It is an arithmetic number, because the mean of its divisors is an integer number (3025050).

Almost surely, 2^20721964 is an apocalyptic number.

It is an amenable number.

20721964 is a deficient number, since it is larger than the sum of its proper divisors (15578636).

20721964 is a wasteful number, since it uses less digits than its factorization.

20721964 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5312 (or 5310 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 31.

The square root of 20721964 is about 4552.1383985991. The cubic root of 20721964 is about 274.6694165318.

The spelling of 20721964 in words is "twenty million, seven hundred twenty-one thousand, nine hundred sixty-four".