21919887 has 12 divisors (see below), whose sum is σ = 34540584. Its totient is φ = 13284720.

The previous prime is 21919847. The next prime is 21919903. The reversal of 21919887 is 78891912.

It is not a de Polignac number, because 21919887 - 2⁶ = 21919823 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21919847) 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, 110608 + ... + 110805.

It is an arithmetic number, because the mean of its divisors is an integer number (2878382).

Almost surely, 2^21919887 is an apocalyptic number.

21919887 is a deficient number, since it is larger than the sum of its proper divisors (12620697).

21919887 is a wasteful number, since it uses less digits than its factorization.

21919887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221430 (or 221427 counting only the distinct ones).

The product of its digits is 72576, while the sum is 45.

The square root of 21919887 is about 4681.8678964704. The cubic root of 21919887 is about 279.8633985041.

The spelling of 21919887 in words is "twenty-one million, nine hundred nineteen thousand, eight hundred eighty-seven".