1821392138 has 16 divisors (see below), whose sum is σ = 2900256840. Its totient is φ = 854916096.

The previous prime is 1821392137. The next prime is 1821392143. The reversal of 1821392138 is 8312931281.

It can be written as a sum of positive squares in 4 ways, for example, as 1269283129 + 552109009 = 35627^2 + 23497^2 .

It is a super-2 number, since 2×1821392138² = 6634938640736422088, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1821392137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 55631 + ... + 82082.

Almost surely, 2^1821392138 is an apocalyptic number.

1821392138 is a deficient number, since it is larger than the sum of its proper divisors (1078864702).

1821392138 is a wasteful number, since it uses less digits than its factorization.

1821392138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138121.

The product of its digits is 20736, while the sum is 38.

The square root of 1821392138 is about 42677.7710055246. The cubic root of 1821392138 is about 1221.2403711159.

The spelling of 1821392138 in words is "one billion, eight hundred twenty-one million, three hundred ninety-two thousand, one hundred thirty-eight".