1661991686902 has 32 divisors (see below), whose sum is σ = 2525942659680. Its totient is φ = 820092349440.

The previous prime is 1661991686897. The next prime is 1661991686903. The reversal of 1661991686902 is 2096861991661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661991686903) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39235078 + ... + 39277414.

It is an arithmetic number, because the mean of its divisors is an integer number (78935708115).

Almost surely, 2^{1661991686902} is an apocalyptic number.

1661991686902 is a deficient number, since it is larger than the sum of its proper divisors (863950972778).

1661991686902 is a wasteful number, since it uses less digits than its factorization.

1661991686902 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43296.

The product of its (nonzero) digits is 15116544, while the sum is 64.

The spelling of 1661991686902 in words is "one trillion, six hundred sixty-one billion, nine hundred ninety-one million, six hundred eighty-six thousand, nine hundred two".