21958427989 has 4 divisors (see below), whose sum is σ = 22014876780. Its totient is φ = 21901979200.

The previous prime is 21958427947. The next prime is 21958427993. The reversal of 21958427989 is 98972485912.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8804631889 + 13153796100 = 93833^2 + 114690^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21958427989 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21958427989.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21958427389) 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, 28223812 + ... + 28224589.

It is an arithmetic number, because the mean of its divisors is an integer number (5503719195).

Almost surely, 2^21958427989 is an apocalyptic number.

It is an amenable number.

21958427989 is a deficient number, since it is larger than the sum of its proper divisors (56448791).

21958427989 is an equidigital number, since it uses as much as digits as its factorization.

21958427989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56448790.

The product of its digits is 26127360, while the sum is 64.

The spelling of 21958427989 in words is "twenty-one billion, nine hundred fifty-eight million, four hundred twenty-seven thousand, nine hundred eighty-nine".