21023487 has 12 divisors (see below), whose sum is σ = 31347264. Its totient is φ = 13563360.

The previous prime is 21023473. The next prime is 21023501. The reversal of 21023487 is 78432012.

It is an interprime number because it is at equal distance from previous prime (21023473) and next prime (21023501).

It is not a de Polignac number, because 21023487 - 2¹⁸ = 20761343 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21023487.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21023417) 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, 37398 + ... + 37955.

It is an arithmetic number, because the mean of its divisors is an integer number (2612272).

Almost surely, 2^21023487 is an apocalyptic number.

21023487 is a deficient number, since it is larger than the sum of its proper divisors (10323777).

21023487 is a wasteful number, since it uses less digits than its factorization.

21023487 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75390 (or 75387 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 21023487 is about 4585.1376206173. The cubic root of 21023487 is about 275.9952346373.

Adding to 21023487 its reverse (78432012), we get a palindrome (99455499).

The spelling of 21023487 in words is "twenty-one million, twenty-three thousand, four hundred eighty-seven".