1990077891 has 8 divisors (see below), whose sum is σ = 2739032064. Its totient is φ = 1283921160.

The previous prime is 1990077889. The next prime is 1990077937. The reversal of 1990077891 is 1987700991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1990077891 - 2¹ = 1990077889 is a prime.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (1990077821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10699251 + ... + 10699436.

It is an arithmetic number, because the mean of its divisors is an integer number (342379008).

Almost surely, 2^1990077891 is an apocalyptic number.

1990077891 is a deficient number, since it is larger than the sum of its proper divisors (748954173).

1990077891 is a wasteful number, since it uses less digits than its factorization.

1990077891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21398721.

The product of its (nonzero) digits is 285768, while the sum is 51.

The square root of 1990077891 is about 44610.2890710204. The cubic root of 1990077891 is about 1257.8340825630.

The spelling of 1990077891 in words is "one billion, nine hundred ninety million, seventy-seven thousand, eight hundred ninety-one".