21641975 has 12 divisors (see below), whose sum is σ = 27762360. Its totient is φ = 16716000.

The previous prime is 21641957. The next prime is 21641981. The reversal of 21641975 is 57914612.

It is a de Polignac number, because none of the positive numbers 2^k-21641975 is a prime.

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, 14201 + ... + 15650.

It is an arithmetic number, because the mean of its divisors is an integer number (2313530).

Almost surely, 2^21641975 is an apocalyptic number.

21641975 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21641975 is a deficient number, since it is larger than the sum of its proper divisors (6120385).

21641975 is a wasteful number, since it uses less digits than its factorization.

21641975 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29890 (or 29885 counting only the distinct ones).

The product of its digits is 15120, while the sum is 35.

The square root of 21641975 is about 4652.0936147073. The cubic root of 21641975 is about 278.6756120755.

The spelling of 21641975 in words is "twenty-one million, six hundred forty-one thousand, nine hundred seventy-five".