21985507 has 4 divisors (see below), whose sum is σ = 22030776. Its totient is φ = 21940240.

The previous prime is 21985501. The next prime is 21985529. The reversal of 21985507 is 70558912.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21985507 - 2³ = 21985499 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21985501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21898 + ... + 22879.

It is an arithmetic number, because the mean of its divisors is an integer number (5507694).

Almost surely, 2^21985507 is an apocalyptic number.

21985507 is a deficient number, since it is larger than the sum of its proper divisors (45269).

21985507 is an equidigital number, since it uses as much as digits as its factorization.

21985507 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45268.

The product of its (nonzero) digits is 25200, while the sum is 37.

The square root of 21985507 is about 4688.8705463043. The cubic root of 21985507 is about 280.1423893127.

The spelling of 21985507 in words is "twenty-one million, nine hundred eighty-five thousand, five hundred seven".