21863889 has 12 divisors (see below), whose sum is σ = 33243600. Its totient is φ = 13808664.

The previous prime is 21863879. The next prime is 21863893. The reversal of 21863889 is 98836812.

21863889 is a `hidden beast` number, since 2 + 1 + 8 + 638 + 8 + 9 = 666.

It is not a de Polignac number, because 21863889 - 2¹³ = 21855697 is a prime.

It is a hoax number, since the sum of its digits (45) 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 (21863879) 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, 63759 + ... + 64100.

It is an arithmetic number, because the mean of its divisors is an integer number (2770300).

Almost surely, 2^21863889 is an apocalyptic number.

It is an amenable number.

21863889 is a deficient number, since it is larger than the sum of its proper divisors (11379711).

21863889 is a wasteful number, since it uses less digits than its factorization.

21863889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127884 (or 127881 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The square root of 21863889 is about 4675.8837667333. The cubic root of 21863889 is about 279.6248760616.

The spelling of 21863889 in words is "twenty-one million, eight hundred sixty-three thousand, eight hundred eighty-nine".