21398571 has 12 divisors (see below), whose sum is σ = 30967872. Its totient is φ = 14238576.

The previous prime is 21398569. The next prime is 21398581. The reversal of 21398571 is 17589312.

It is not a de Polignac number, because 21398571 - 2¹ = 21398569 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21398521) 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, 3505 + ... + 7421.

It is an arithmetic number, because the mean of its divisors is an integer number (2580656).

Almost surely, 2^21398571 is an apocalyptic number.

21398571 is a deficient number, since it is larger than the sum of its proper divisors (9569301).

21398571 is a wasteful number, since it uses less digits than its factorization.

21398571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4530 (or 4527 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 21398571 is about 4625.8589472659. The cubic root of 21398571 is about 277.6269300018.

The spelling of 21398571 in words is "twenty-one million, three hundred ninety-eight thousand, five hundred seventy-one".