1986777639961 has 3 divisors (see below), whose sum is σ = 1986779049493. Its totient is φ = 1986776230430.

The previous prime is 1986777639919. The next prime is 1986777640079. The reversal of 1986777639961 is 1699367776891.

The square root of 1986777639961 is 1409531.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 1986777639961 - 2³⁹ = 1437021826073 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1986777639901) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 704766 + ... + 2114296.

Almost surely, 2^{1986777639961} is an apocalyptic number.

1986777639961 is the 1409531-st square number.

1986777639961 is the 704766-th centered octagonal number.

It is an amenable number.

1986777639961 is a deficient number, since it is larger than the sum of its proper divisors (1409532).

1986777639961 is an frugal number, since it uses more digits than its factorization.

1986777639961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2819062 (or 1409531 counting only the distinct ones).

The product of its digits is 1296243648, while the sum is 79.

The spelling of 1986777639961 in words is "one trillion, nine hundred eighty-six billion, seven hundred seventy-seven million, six hundred thirty-nine thousand, nine hundred sixty-one".