1261776771621 has 32 divisors (see below), whose sum is σ = 1933919971200. Its totient is φ = 812109916800.

The previous prime is 1261776771617. The next prime is 1261776771631.

1261776771621 is a `hidden beast` number, since 1 + 2 + 6 + 1 + 7 + 7 + 6 + 7 + 7 + 1 + 621 = 666.

1261776771621 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1261776771621 - 2² = 1261776771617 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261776771601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10264321 + ... + 10386521.

It is an arithmetic number, because the mean of its divisors is an integer number (60434999100).

Almost surely, 2^{1261776771621} is an apocalyptic number.

It is an amenable number.

1261776771621 is a deficient number, since it is larger than the sum of its proper divisors (672143199579).

1261776771621 is a wasteful number, since it uses less digits than its factorization.

1261776771621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135426 (or 135420 counting only the distinct ones).

The product of its digits is 2074464, while the sum is 54.

The spelling of 1261776771621 in words is "one trillion, two hundred sixty-one billion, seven hundred seventy-six million, seven hundred seventy-one thousand, six hundred twenty-one".