18993643440 has 80 divisors (see below), whose sum is σ = 59878310400. Its totient is φ = 4979120896.

The previous prime is 18993643423. The next prime is 18993643457. The reversal of 18993643440 is 4434639981.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (18993643423) and next prime (18993643457).

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×18993643440² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 656520 + ... + 684839.

It is an arithmetic number, because the mean of its divisors is an integer number (748478880).

Almost surely, 2^18993643440 is an apocalyptic number.

18993643440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18993643440 is an abundant number, since it is smaller than the sum of its proper divisors (40884666960).

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

18993643440 is a wasteful number, since it uses less digits than its factorization.

18993643440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1341434 (or 1341428 counting only the distinct ones).

The product of its (nonzero) digits is 2239488, while the sum is 51.

The spelling of 18993643440 in words is "eighteen billion, nine hundred ninety-three million, six hundred forty-three thousand, four hundred forty".