21372587 has 8 divisors (see below), whose sum is σ = 23821200. Its totient is φ = 19056384.

The previous prime is 21372577. The next prime is 21372629. The reversal of 21372587 is 78527312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21372587 - 2¹⁸ = 21110443 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21372577) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32762 + ... + 33407.

It is an arithmetic number, because the mean of its divisors is an integer number (2977650).

Almost surely, 2^21372587 is an apocalyptic number.

21372587 is a deficient number, since it is larger than the sum of its proper divisors (2448613).

21372587 is a wasteful number, since it uses less digits than its factorization.

21372587 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66205.

The product of its digits is 23520, while the sum is 35.

The square root of 21372587 is about 4623.0495346686. The cubic root of 21372587 is about 277.5145115913.

Adding to 21372587 its reverse (78527312), we get a palindrome (99899899).

The spelling of 21372587 in words is "twenty-one million, three hundred seventy-two thousand, five hundred eighty-seven".