1990191061 has 4 divisors (see below), whose sum is σ = 1992564000. Its totient is φ = 1987818124.

The previous prime is 1990191031. The next prime is 1990191079. The reversal of 1990191061 is 1601910991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1601910991 = 1319 ⋅1214489.

It is a cyclic number.

It is not a de Polignac number, because 1990191061 - 2¹¹ = 1990189013 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1990191061.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1990191031) 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, 1185211 + ... + 1186888.

It is an arithmetic number, because the mean of its divisors is an integer number (498141000).

Almost surely, 2^1990191061 is an apocalyptic number.

It is an amenable number.

1990191061 is a deficient number, since it is larger than the sum of its proper divisors (2372939).

1990191061 is an equidigital number, since it uses as much as digits as its factorization.

1990191061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2372938.

The product of its (nonzero) digits is 4374, while the sum is 37.

The square root of 1990191061 is about 44611.5574823386. The cubic root of 1990191061 is about 1257.8579252453.

The spelling of 1990191061 in words is "one billion, nine hundred ninety million, one hundred ninety-one thousand, sixty-one".