21987624959 has 4 divisors (see below), whose sum is σ = 21988316616. Its totient is φ = 21986933304.

The previous prime is 21987624949. The next prime is 21987625003. The reversal of 21987624959 is 95942678912.

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 21987624959 - 2³² = 17692657663 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21987624949) 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, 295724 + ... + 362529.

It is an arithmetic number, because the mean of its divisors is an integer number (5497079154).

Almost surely, 2^21987624959 is an apocalyptic number.

21987624959 is a deficient number, since it is larger than the sum of its proper divisors (691657).

21987624959 is an equidigital number, since it uses as much as digits as its factorization.

21987624959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 691656.

The product of its digits is 19595520, while the sum is 62.

The spelling of 21987624959 in words is "twenty-one billion, nine hundred eighty-seven million, six hundred twenty-four thousand, nine hundred fifty-nine".