20972945 has 16 divisors (see below), whose sum is σ = 29756160. Its totient is φ = 13884864.

The previous prime is 20972933. The next prime is 20972977. The reversal of 20972945 is 54927902.

It is not a de Polignac number, because 20972945 - 2¹⁶ = 20907409 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20972899 and 20972908.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9317 + ... + 11346.

It is an arithmetic number, because the mean of its divisors is an integer number (1859760).

Almost surely, 2^20972945 is an apocalyptic number.

It is an amenable number.

20972945 is a deficient number, since it is larger than the sum of its proper divisors (8783215).

20972945 is a wasteful number, since it uses less digits than its factorization.

20972945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20704.

The product of its (nonzero) digits is 45360, while the sum is 38.

The square root of 20972945 is about 4579.6228010612. The cubic root of 20972945 is about 275.7738862549.

The spelling of 20972945 in words is "twenty million, nine hundred seventy-two thousand, nine hundred forty-five".