1990336891 has 2 divisors, whose sum is σ = 1990336892. Its totient is φ = 1990336890.

The previous prime is 1990336847. The next prime is 1990336919. The reversal of 1990336891 is 1986330991.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1990336891 - 2²⁵ = 1956782459 is a prime.

It is a super-2 number, since 2×1990336891² = 7922881879351091762, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1990336291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995168445 + 995168446.

It is an arithmetic number, because the mean of its divisors is an integer number (995168446).

Almost surely, 2^1990336891 is an apocalyptic number.

1990336891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1990336891 is an equidigital number, since it uses as much as digits as its factorization.

1990336891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 314928, while the sum is 49.

The square root of 1990336891 is about 44613.1918943265. The cubic root of 1990336891 is about 1257.8886474114. Note that the first 3 decimals are identical.

The spelling of 1990336891 in words is "one billion, nine hundred ninety million, three hundred thirty-six thousand, eight hundred ninety-one".