20900945 has 8 divisors (see below), whose sum is σ = 27010536. Its totient is φ = 15434496.

The previous prime is 20900933. The next prime is 20900981. The reversal of 20900945 is 54900902.

It can be written as a sum of positive squares in 4 ways, for example, as 4892944 + 16008001 = 2212^2 + 4001^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20900945 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 160712 + ... + 160841.

It is an arithmetic number, because the mean of its divisors is an integer number (3376317).

Almost surely, 2^20900945 is an apocalyptic number.

It is an amenable number.

20900945 is a deficient number, since it is larger than the sum of its proper divisors (6109591).

20900945 is a wasteful number, since it uses less digits than its factorization.

20900945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321571.

The product of its (nonzero) digits is 3240, while the sum is 29.

The square root of 20900945 is about 4571.7551334252. The cubic root of 20900945 is about 275.4579477164.

The spelling of 20900945 in words is "twenty million, nine hundred thousand, nine hundred forty-five".