21803857 has 2 divisors, whose sum is σ = 21803858. Its totient is φ = 21803856.

The previous prime is 21803827. The next prime is 21803861. The reversal of 21803857 is 75830812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15928081 + 5875776 = 3991^2 + 2424^2 .

It is a cyclic number.

It is not a de Polignac number, because 21803857 - 2⁷ = 21803729 is a prime.

It is not a weakly prime, because it can be changed into another prime (21803827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10901928 + 10901929.

It is an arithmetic number, because the mean of its divisors is an integer number (10901929).

Almost surely, 2^21803857 is an apocalyptic number.

It is an amenable number.

21803857 is a deficient number, since it is larger than the sum of its proper divisors (1).

21803857 is an equidigital number, since it uses as much as digits as its factorization.

21803857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13440, while the sum is 34.

The square root of 21803857 is about 4669.4600330231. The cubic root of 21803857 is about 279.3687181013.

The spelling of 21803857 in words is "twenty-one million, eight hundred three thousand, eight hundred fifty-seven".