1812821109 has 16 divisors (see below), whose sum is σ = 2701145664. Its totient is φ = 1071881600.

The previous prime is 1812821057. The next prime is 1812821113. The reversal of 1812821109 is 9011282181.

It is a cyclic number.

It is not a de Polignac number, because 1812821109 - 2⁷ = 1812820981 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a self number, because there is not a number n which added to its sum of digits gives 1812821109.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1812821009) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 668574 + ... + 671279.

It is an arithmetic number, because the mean of its divisors is an integer number (168821604).

Almost surely, 2^1812821109 is an apocalyptic number.

It is an amenable number.

1812821109 is a deficient number, since it is larger than the sum of its proper divisors (888324555).

1812821109 is a wasteful number, since it uses less digits than its factorization.

1812821109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1339908.

The product of its (nonzero) digits is 2304, while the sum is 33.

The square root of 1812821109 is about 42577.2369817488. The cubic root of 1812821109 is about 1219.3217382355.

The spelling of 1812821109 in words is "one billion, eight hundred twelve million, eight hundred twenty-one thousand, one hundred nine".