21999975 has 24 divisors (see below), whose sum is σ = 36582480. Its totient is φ = 11665920.

The previous prime is 21999973. The next prime is 21999977. The reversal of 21999975 is 57999912.

It is an interprime number because it is at equal distance from previous prime (21999973) and next prime (21999977).

It is not a de Polignac number, because 21999975 - 2¹ = 21999973 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21999973) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14031 + ... + 15519.

It is an arithmetic number, because the mean of its divisors is an integer number (1524270).

Almost surely, 2^21999975 is an apocalyptic number.

21999975 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21999975 is a deficient number, since it is larger than the sum of its proper divisors (14582505).

21999975 is a wasteful number, since it uses less digits than its factorization.

21999975 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1699 (or 1694 counting only the distinct ones).

The product of its digits is 459270, while the sum is 51.

The square root of 21999975 is about 4690.4130948137. The cubic root of 21999975 is about 280.2038269276.

The spelling of 21999975 in words is "twenty-one million, nine hundred ninety-nine thousand, nine hundred seventy-five".