21023387 has 12 divisors (see below), whose sum is σ = 26410608. Its totient is φ = 16381200.

The previous prime is 21023383. The next prime is 21023393. The reversal of 21023387 is 78332012.

It is not a de Polignac number, because 21023387 - 2² = 21023383 is a prime.

It is a hoax number, since the sum of its digits (26) 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 (21023381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11564 + ... + 13257.

It is an arithmetic number, because the mean of its divisors is an integer number (2200884).

Almost surely, 2^21023387 is an apocalyptic number.

21023387 is a deficient number, since it is larger than the sum of its proper divisors (5387221).

21023387 is a wasteful number, since it uses less digits than its factorization.

21023387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24850 (or 24839 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 26.

The square root of 21023387 is about 4585.1267158062. The cubic root of 21023387 is about 275.9947970384.

Adding to 21023387 its reverse (78332012), we get a palindrome (99355399).

The spelling of 21023387 in words is "twenty-one million, twenty-three thousand, three hundred eighty-seven".