1813778172 has 72 divisors (see below), whose sum is σ = 4767012432. Its totient is φ = 581011200.

The previous prime is 1813778129. The next prime is 1813778173. The reversal of 1813778172 is 2718773181.

It is a happy number.

It is a super-3 number, since 3×1813778172³ (a number of 29 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1813778173) 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, 89722 + ... + 108062.

It is an arithmetic number, because the mean of its divisors is an integer number (66208506).

Almost surely, 2^1813778172 is an apocalyptic number.

1813778172 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 1813778172, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2383506216).

1813778172 is an abundant number, since it is smaller than the sum of its proper divisors (2953234260).

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

1813778172 is a wasteful number, since it uses less digits than its factorization.

1813778172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18459 (or 18454 counting only the distinct ones).

The product of its digits is 131712, while the sum is 45.

The square root of 1813778172 is about 42588.4746380990. The cubic root of 1813778172 is about 1219.5362772233.

The spelling of 1813778172 in words is "one billion, eight hundred thirteen million, seven hundred seventy-eight thousand, one hundred seventy-two".