21398211 has 24 divisors (see below), whose sum is σ = 32497920. Its totient is φ = 13541616.

The previous prime is 21398191. The next prime is 21398227. The reversal of 21398211 is 11289312.

It is not a de Polignac number, because 21398211 - 2⁹ = 21397699 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21398261) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 34260 + ... + 34878.

It is an arithmetic number, because the mean of its divisors is an integer number (1354080).

Almost surely, 2^21398211 is an apocalyptic number.

21398211 is a deficient number, since it is larger than the sum of its proper divisors (11099709).

21398211 is a wasteful number, since it uses less digits than its factorization.

21398211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 815 (or 812 counting only the distinct ones).

The product of its digits is 864, while the sum is 27.

The square root of 21398211 is about 4625.8200354099. The cubic root of 21398211 is about 277.6253731026.

It can be divided in two parts, 21398 and 211, that added together give a square (21609 = 147²).

The spelling of 21398211 in words is "twenty-one million, three hundred ninety-eight thousand, two hundred eleven".