21258387 has 12 divisors (see below), whose sum is σ = 31536960. Its totient is φ = 13789008.

The previous prime is 21258373. The next prime is 21258401. The reversal of 21258387 is 78385212.

21258387 is a `hidden beast` number, since 21 + 258 + 387 = 666.

21258387 is an esthetic number in base 7, because in such base its adjacent digits differ by 1.

It is an interprime number because it is at equal distance from previous prime (21258373) and next prime (21258401).

It is not a de Polignac number, because 21258387 - 2¹⁸ = 20996243 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21258487) 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, 31587 + ... + 32252.

It is an arithmetic number, because the mean of its divisors is an integer number (2628080).

Almost surely, 2^21258387 is an apocalyptic number.

21258387 is a deficient number, since it is larger than the sum of its proper divisors (10278573).

21258387 is a wasteful number, since it uses less digits than its factorization.

21258387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63882 (or 63879 counting only the distinct ones).

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

The square root of 21258387 is about 4610.6818367786. The cubic root of 21258387 is about 277.0193481339.

The spelling of 21258387 in words is "twenty-one million, two hundred fifty-eight thousand, three hundred eighty-seven".