1904090861 has 2 divisors, whose sum is σ = 1904090862. Its totient is φ = 1904090860.

The previous prime is 1904090849. The next prime is 1904090917. The reversal of 1904090861 is 1680904091.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1673628100 + 230462761 = 40910^2 + 15181^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1904090861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1904090821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 952045430 + 952045431.

It is an arithmetic number, because the mean of its divisors is an integer number (952045431).

Almost surely, 2^1904090861 is an apocalyptic number.

It is an amenable number.

1904090861 is a deficient number, since it is larger than the sum of its proper divisors (1).

1904090861 is an equidigital number, since it uses as much as digits as its factorization.

1904090861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15552, while the sum is 38.

The square root of 1904090861 is about 43635.8895978987. The cubic root of 1904090861 is about 1239.4506023086.

It can be divided in two parts, 19040 and 90861, that added together give a palindrome (109901).

The spelling of 1904090861 in words is "one billion, nine hundred four million, ninety thousand, eight hundred sixty-one".