20900947 has 4 divisors (see below), whose sum is σ = 21345696. Its totient is φ = 20456200.

The previous prime is 20900933. The next prime is 20900981. The reversal of 20900947 is 74900902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74900902 = 2 ⋅37450451.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20900947 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20900987) 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, 222304 + ... + 222397.

It is an arithmetic number, because the mean of its divisors is an integer number (5336424).

Almost surely, 2^20900947 is an apocalyptic number.

20900947 is a deficient number, since it is larger than the sum of its proper divisors (444749).

20900947 is an equidigital number, since it uses as much as digits as its factorization.

20900947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 444748.

The product of its (nonzero) digits is 4536, while the sum is 31.

The square root of 20900947 is about 4571.7553521596. The cubic root of 20900947 is about 275.4579565026.

The spelling of 20900947 in words is "twenty million, nine hundred thousand, nine hundred forty-seven".