1991402766 has 16 divisors (see below), whose sum is σ = 4425339600. Its totient is φ = 663800904.

The previous prime is 1991402747. The next prime is 1991402771. The reversal of 1991402766 is 6672041991.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18438861 + ... + 18438968.

It is an arithmetic number, because the mean of its divisors is an integer number (276583725).

Almost surely, 2^1991402766 is an apocalyptic number.

1991402766 is an abundant number, since it is smaller than the sum of its proper divisors (2433936834).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1991402766 is a wasteful number, since it uses less digits than its factorization.

1991402766 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36877840 (or 36877834 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 45.

The square root of 1991402766 is about 44625.1360334061. The cubic root of 1991402766 is about 1258.1131509120.

The spelling of 1991402766 in words is "one billion, nine hundred ninety-one million, four hundred two thousand, seven hundred sixty-six".