18871420981 has 4 divisors (see below), whose sum is σ = 21567338272. Its totient is φ = 16175503692.

The previous prime is 18871420963. The next prime is 18871420999. The reversal of 18871420981 is 18902417881.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (18871420963) and next prime (18871420999).

It is a cyclic number.

It is not a de Polignac number, because 18871420981 - 2⁷ = 18871420853 is a prime.

It is a super-2 number, since 2×18871420981² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18871420921) 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, 1347958635 + ... + 1347958648.

It is an arithmetic number, because the mean of its divisors is an integer number (5391834568).

Almost surely, 2^18871420981 is an apocalyptic number.

It is an amenable number.

18871420981 is a deficient number, since it is larger than the sum of its proper divisors (2695917291).

18871420981 is an equidigital number, since it uses as much as digits as its factorization.

18871420981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2695917290.

The product of its (nonzero) digits is 258048, while the sum is 49.

The spelling of 18871420981 in words is "eighteen billion, eight hundred seventy-one million, four hundred twenty thousand, nine hundred eighty-one".