21523887 has 120 divisors (see below), whose sum is σ = 44692560. Its totient is φ = 10160640.

The previous prime is 21523847. The next prime is 21523891. The reversal of 21523887 is 78832512.

It is not a de Polignac number, because 21523887 - 2⁸ = 21523631 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21523847) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 742189 + ... + 742217.

It is an arithmetic number, because the mean of its divisors is an integer number (372438).

Almost surely, 2^21523887 is an apocalyptic number.

21523887 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21523887 is an abundant number, since it is smaller than the sum of its proper divisors (23168673).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21523887 is a wasteful number, since it uses less digits than its factorization.

21523887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83 (or 67 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 21523887 is about 4639.3843341547. The cubic root of 21523887 is about 278.1678290648.

The spelling of 21523887 in words is "twenty-one million, five hundred twenty-three thousand, eight hundred eighty-seven".