20657217 has 16 divisors (see below), whose sum is σ = 31805312. Its totient is φ = 11681280.

The previous prime is 20657209. The next prime is 20657233. The reversal of 20657217 is 71275602.

It is not a de Polignac number, because 20657217 - 2³ = 20657209 is a prime.

It is a super-2 number, since 2×20657217² = 853441228370178, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20657297) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 3034 + ... + 7107.

It is an arithmetic number, because the mean of its divisors is an integer number (1987832).

Almost surely, 2^20657217 is an apocalyptic number.

It is an amenable number.

20657217 is a deficient number, since it is larger than the sum of its proper divisors (11148095).

20657217 is a wasteful number, since it uses less digits than its factorization.

20657217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10248.

The product of its (nonzero) digits is 5880, while the sum is 30.

The square root of 20657217 is about 4545.0211220631. The cubic root of 20657217 is about 274.3830444591.

The spelling of 20657217 in words is "twenty million, six hundred fifty-seven thousand, two hundred seventeen".