1821815172 has 48 divisors (see below), whose sum is σ = 4726149120. Its totient is φ = 606895776.

The previous prime is 1821815141. The next prime is 1821815189. The reversal of 1821815172 is 2715181281.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 211453 + ... + 219899.

It is an arithmetic number, because the mean of its divisors is an integer number (98461440).

Almost surely, 2^1821815172 is an apocalyptic number.

1821815172 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1821815172 is an abundant number, since it is smaller than the sum of its proper divisors (2904333948).

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

1821815172 is a wasteful number, since it uses less digits than its factorization.

1821815172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10457 (or 10449 counting only the distinct ones).

The product of its digits is 8960, while the sum is 36.

The square root of 1821815172 is about 42682.7268575943. The cubic root of 1821815172 is about 1221.3349116593.

The spelling of 1821815172 in words is "one billion, eight hundred twenty-one million, eight hundred fifteen thousand, one hundred seventy-two".