21987962427 has 4 divisors (see below), whose sum is σ = 29317283240. Its totient is φ = 14658641616.

The previous prime is 21987962419. The next prime is 21987962449. The reversal of 21987962427 is 72426978912.

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

It is not a de Polignac number, because 21987962427 - 2³ = 21987962419 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21987962417) 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, 3664660402 + ... + 3664660407.

It is an arithmetic number, because the mean of its divisors is an integer number (7329320810).

Almost surely, 2^21987962427 is an apocalyptic number.

21987962427 is a deficient number, since it is larger than the sum of its proper divisors (7329320813).

21987962427 is an equidigital number, since it uses as much as digits as its factorization.

21987962427 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7329320812.

The product of its digits is 6096384, while the sum is 57.

The spelling of 21987962427 in words is "twenty-one billion, nine hundred eighty-seven million, nine hundred sixty-two thousand, four hundred twenty-seven".