21500075 has 12 divisors (see below), whose sum is σ = 26781768. Its totient is φ = 17121600.

The previous prime is 21500069. The next prime is 21500111. The reversal of 21500075 is 57000512.

It is not a de Polignac number, because 21500075 - 2¹⁴ = 21483691 is a prime.

It is a Duffinian 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, 3980 + ... + 7670.

It is an arithmetic number, because the mean of its divisors is an integer number (2231814).

Almost surely, 2^21500075 is an apocalyptic number.

21500075 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21500075 is a deficient number, since it is larger than the sum of its proper divisors (5281693).

21500075 is a wasteful number, since it uses less digits than its factorization.

21500075 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3934 (or 3929 counting only the distinct ones).

The product of its (nonzero) digits is 350, while the sum is 20.

The square root of 21500075 is about 4636.8173351988. The cubic root of 21500075 is about 278.0652116570.

Adding to 21500075 its reverse (57000512), we get a palindrome (78500587).

The spelling of 21500075 in words is "twenty-one million, five hundred thousand, seventy-five".