20947057 has 4 divisors (see below), whose sum is σ = 20978676. Its totient is φ = 20915440.

The previous prime is 20947033. The next prime is 20947061. The reversal of 20947057 is 75074902.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15358561 + 5588496 = 3919^2 + 2364^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20947057 is a prime.

It is a super-2 number, since 2×20947057² = 877558393922498, which contains 22 as substring.

It is a Duffinian number.

It is a zygodrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (20947027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14794 + ... + 16147.

It is an arithmetic number, because the mean of its divisors is an integer number (5244669).

Almost surely, 2^20947057 is an apocalyptic number.

It is an amenable number.

20947057 is a deficient number, since it is larger than the sum of its proper divisors (31619).

20947057 is an equidigital number, since it uses as much as digits as its factorization.

20947057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31618.

The product of its (nonzero) digits is 17640, while the sum is 34.

The square root of 20947057 is about 4576.7954946665. The cubic root of 20947057 is about 275.6603721724.

The spelling of 20947057 in words is "twenty million, nine hundred forty-seven thousand, fifty-seven".