21855357 has 12 divisors (see below), whose sum is σ = 32657820. Its totient is φ = 14067648.

The previous prime is 21855349. The next prime is 21855367. The reversal of 21855357 is 75355812.

It can be written as a sum of positive squares in 2 ways, for example, as 8415801 + 13439556 = 2901^2 + 3666^2 .

It is not a de Polignac number, because 21855357 - 2³ = 21855349 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21855367) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41608 + ... + 42129.

It is an arithmetic number, because the mean of its divisors is an integer number (2721485).

Almost surely, 2^21855357 is an apocalyptic number.

It is an amenable number.

21855357 is a deficient number, since it is larger than the sum of its proper divisors (10802463).

21855357 is a wasteful number, since it uses less digits than its factorization.

21855357 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83772 (or 83769 counting only the distinct ones).

The product of its digits is 42000, while the sum is 36.

The square root of 21855357 is about 4674.9713368105. The cubic root of 21855357 is about 279.5884984248.

The spelling of 21855357 in words is "twenty-one million, eight hundred fifty-five thousand, three hundred fifty-seven".