20857951 has 8 divisors (see below), whose sum is σ = 21265200. Its totient is φ = 20454720.

The previous prime is 20857943. The next prime is 20857957. The reversal of 20857951 is 15975802.

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

It is a cyclic number.

It is not a de Polignac number, because 20857951 - 2³ = 20857943 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20857951.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20857957) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10765 + ... + 12553.

It is an arithmetic number, because the mean of its divisors is an integer number (2658150).

Almost surely, 2^20857951 is an apocalyptic number.

20857951 is a deficient number, since it is larger than the sum of its proper divisors (407249).

20857951 is a wasteful number, since it uses less digits than its factorization.

20857951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2009.

The product of its (nonzero) digits is 25200, while the sum is 37.

The square root of 20857951 is about 4567.0505799695. The cubic root of 20857951 is about 275.2689424057.

The spelling of 20857951 in words is "twenty million, eight hundred fifty-seven thousand, nine hundred fifty-one".