18987551856 has 120 divisors (see below), whose sum is σ = 65401612640. Its totient is φ = 5007702528.

The previous prime is 18987551851. The next prime is 18987551893. The reversal of 18987551856 is 65815578981.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a junction number, because it is equal to n+sod(n) for n = 18987551793 and 18987551802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18987551851) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 711391 + ... + 737598.

Almost surely, 2^18987551856 is an apocalyptic number.

18987551856 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

18987551856 is an abundant number, since it is smaller than the sum of its proper divisors (46414060784).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18987551856 is a wasteful number, since it uses less digits than its factorization.

18987551856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1449023 (or 1449014 counting only the distinct ones).

The product of its digits is 24192000, while the sum is 63.

The spelling of 18987551856 in words is "eighteen billion, nine hundred eighty-seven million, five hundred fifty-one thousand, eight hundred fifty-six".