18291781632 has 156 divisors (see below), whose sum is σ = 50428710600. Its totient is φ = 5896765440.

The previous prime is 18291781583. The next prime is 18291781633. The reversal of 18291781632 is 23618719281.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18291781633) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11807994 + ... + 11809542.

Almost surely, 2^18291781632 is an apocalyptic number.

18291781632 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 18291781632, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25214355300).

18291781632 is an abundant number, since it is smaller than the sum of its proper divisors (32136928968).

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

18291781632 is an equidigital number, since it uses as much as digits as its factorization.

18291781632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1638 (or 1585 counting only the distinct ones).

The product of its digits is 290304, while the sum is 48.

The spelling of 18291781632 in words is "eighteen billion, two hundred ninety-one million, seven hundred eighty-one thousand, six hundred thirty-two".