21004975 has 12 divisors (see below), whose sum is σ = 27417640. Its totient is φ = 15919200.

The previous prime is 21004931. The next prime is 21004981. The reversal of 21004975 is 57940012.

It is a happy number.

It is not a de Polignac number, because 21004975 - 2⁷ = 21004847 is a prime.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21636 + ... + 22585.

Almost surely, 2^21004975 is an apocalyptic number.

21004975 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21004975 is a deficient number, since it is larger than the sum of its proper divisors (6412665).

21004975 is a wasteful number, since it uses less digits than its factorization.

21004975 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44250 (or 44245 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21004975 is about 4583.1184798126. The cubic root of 21004975 is about 275.9142026604.

Adding to 21004975 its reverse (57940012), we get a palindrome (78944987).

The spelling of 21004975 in words is "twenty-one million, four thousand, nine hundred seventy-five".