1821072645 has 64 divisors (see below), whose sum is σ = 3713149440. Its totient is φ = 829522944.

The previous prime is 1821072641. The next prime is 1821072647. The reversal of 1821072645 is 5462701281.

1821072645 is a `hidden beast` number, since 1 + 8 + 2 + 1 + 0 + 7 + 2 + 645 = 666.

It is not a de Polignac number, because 1821072645 - 2² = 1821072641 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1821072641) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 273597 + ... + 280173.

It is an arithmetic number, because the mean of its divisors is an integer number (58017960).

Almost surely, 2^1821072645 is an apocalyptic number.

1821072645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1821072645 is an abundant number, since it is smaller than the sum of its proper divisors (1892076795).

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

1821072645 is a wasteful number, since it uses less digits than its factorization.

1821072645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6891 (or 6885 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 36.

The square root of 1821072645 is about 42674.0277569390. The cubic root of 1821072645 is about 1221.1689604336.

The spelling of 1821072645 in words is "one billion, eight hundred twenty-one million, seventy-two thousand, six hundred forty-five".