20856953 has 4 divisors (see below), whose sum is σ = 22461348. Its totient is φ = 19252560.

The previous prime is 20856949. The next prime is 20856961. The reversal of 20856953 is 35965802.

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 5396329 + 15460624 = 2323^2 + 3932^2 .

It is a cyclic number.

It is not a de Polignac number, because 20856953 - 2² = 20856949 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20850953) 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, 802178 + ... + 802203.

It is an arithmetic number, because the mean of its divisors is an integer number (5615337).

Almost surely, 2^20856953 is an apocalyptic number.

It is an amenable number.

20856953 is a deficient number, since it is larger than the sum of its proper divisors (1604395).

20856953 is a wasteful number, since it uses less digits than its factorization.

20856953 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1604394.

The product of its (nonzero) digits is 64800, while the sum is 38.

The square root of 20856953 is about 4566.9413177750. The cubic root of 20856953 is about 275.2645520290.

The spelling of 20856953 in words is "twenty million, eight hundred fifty-six thousand, nine hundred fifty-three".