21252587 has 4 divisors (see below), whose sum is σ = 21380016. Its totient is φ = 21125160.

The previous prime is 21252571. The next prime is 21252589. The reversal of 21252587 is 78525212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21252587 - 2⁴ = 21252571 is a prime.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21252589) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63464 + ... + 63797.

It is an arithmetic number, because the mean of its divisors is an integer number (5345004).

Almost surely, 2^21252587 is an apocalyptic number.

21252587 is a deficient number, since it is larger than the sum of its proper divisors (127429).

21252587 is a wasteful number, since it uses less digits than its factorization.

21252587 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127428.

The product of its digits is 11200, while the sum is 32.

The square root of 21252587 is about 4610.0528196540. The cubic root of 21252587 is about 276.9941524569.

Adding to 21252587 its reverse (78525212), we get a palindrome (99777799).

The spelling of 21252587 in words is "twenty-one million, two hundred fifty-two thousand, five hundred eighty-seven".