1865837921 has 2 divisors, whose sum is σ = 1865837922. Its totient is φ = 1865837920.

The previous prime is 1865837891. The next prime is 1865837923. The reversal of 1865837921 is 1297385681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1694227921 + 171610000 = 41161^2 + 13100^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1865837921 is a prime.

It is a super-2 number, since 2×1865837921² = 6962702294883204482, which contains 22 as substring.

Together with 1865837923, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1865837921.

It is not a weakly prime, because it can be changed into another prime (1865837923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 932918960 + 932918961.

It is an arithmetic number, because the mean of its divisors is an integer number (932918961).

Almost surely, 2^1865837921 is an apocalyptic number.

It is an amenable number.

1865837921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1865837921 is an equidigital number, since it uses as much as digits as its factorization.

1865837921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 725760, while the sum is 50.

The square root of 1865837921 is about 43195.3460571854. The cubic root of 1865837921 is about 1231.0942563498.

The spelling of 1865837921 in words is "one billion, eight hundred sixty-five million, eight hundred thirty-seven thousand, nine hundred twenty-one".