1990775957 has 4 divisors (see below), whose sum is σ = 1993492620. Its totient is φ = 1988059296.

The previous prime is 1990775947. The next prime is 1990775987. The reversal of 1990775957 is 7595770991.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1979004196 + 11771761 = 44486^2 + 3431^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1990775957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1990775896 and 1990775905.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1990775947) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1357232 + ... + 1358697.

It is an arithmetic number, because the mean of its divisors is an integer number (498373155).

Almost surely, 2^1990775957 is an apocalyptic number.

It is an amenable number.

1990775957 is a deficient number, since it is larger than the sum of its proper divisors (2716663).

1990775957 is an equidigital number, since it uses as much as digits as its factorization.

1990775957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2716662.

The product of its (nonzero) digits is 6251175, while the sum is 59.

The square root of 1990775957 is about 44618.1124320606. The cubic root of 1990775957 is about 1257.9811368676.

The spelling of 1990775957 in words is "one billion, nine hundred ninety million, seven hundred seventy-five thousand, nine hundred fifty-seven".