1821378756 has 24 divisors (see below), whose sum is σ = 4396432320. Its totient is φ = 586190752.

The previous prime is 1821378721. The next prime is 1821378781. The reversal of 1821378756 is 6578731281.

It is a happy number.

It is a hoax number, since the sum of its digits (48) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2616576 + ... + 2617271.

It is an arithmetic number, because the mean of its divisors is an integer number (183184680).

Almost surely, 2^1821378756 is an apocalyptic number.

It is an amenable number.

1821378756 is an abundant number, since it is smaller than the sum of its proper divisors (2575053564).

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

1821378756 is a wasteful number, since it uses less digits than its factorization.

1821378756 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5233883 (or 5233881 counting only the distinct ones).

The product of its digits is 564480, while the sum is 48.

The square root of 1821378756 is about 42677.6142257273. The cubic root of 1821378756 is about 1221.2373802390.

It can be divided in two parts, 18213 and 78756, that added together give a palindrome (96969).

The spelling of 1821378756 in words is "one billion, eight hundred twenty-one million, three hundred seventy-eight thousand, seven hundred fifty-six".