21814857 has 6 divisors (see below), whose sum is σ = 31510362. Its totient is φ = 14543232.

The previous prime is 21814843. The next prime is 21814901. The reversal of 21814857 is 75841812.

It can be written as a sum of positive squares in only one way, i.e., 21261321 + 553536 = 4611^2 + 744^2 .

It is not a de Polignac number, because 21814857 - 2⁴ = 21814841 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21814817) 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 5 ways as a sum of consecutive naturals, for example, 1211928 + ... + 1211945.

It is an arithmetic number, because the mean of its divisors is an integer number (5251727).

Almost surely, 2^21814857 is an apocalyptic number.

It is an amenable number.

21814857 is a deficient number, since it is larger than the sum of its proper divisors (9695505).

21814857 is a wasteful number, since it uses less digits than its factorization.

21814857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2423879 (or 2423876 counting only the distinct ones).

The product of its digits is 17920, while the sum is 36.

The square root of 21814857 is about 4670.6377508858. The cubic root of 21814857 is about 279.4156905133.

The spelling of 21814857 in words is "twenty-one million, eight hundred fourteen thousand, eight hundred fifty-seven".