18521943972 has 96 divisors (see below), whose sum is σ = 52836795648. Its totient is φ = 4929306624.

The previous prime is 18521943949. The next prime is 18521944027. The reversal of 18521943972 is 27934912581.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 71658 + ... + 205374.

It is an arithmetic number, because the mean of its divisors is an integer number (550383288).

Almost surely, 2^18521943972 is an apocalyptic number.

18521943972 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18521943972, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26418397824).

18521943972 is an abundant number, since it is smaller than the sum of its proper divisors (34314851676).

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

18521943972 is a wasteful number, since it uses less digits than its factorization.

18521943972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133845 (or 133843 counting only the distinct ones).

The product of its digits is 1088640, while the sum is 51.

The spelling of 18521943972 in words is "eighteen billion, five hundred twenty-one million, nine hundred forty-three thousand, nine hundred seventy-two".