1277666254921 has 27 divisors (see below), whose sum is σ = 1500584102901. Its totient is φ = 1084691389824.

The previous prime is 1277666254861. The next prime is 1277666254961. The reversal of 1277666254921 is 1294526667721.

The square root of 1277666254921 is 1130339.

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

It can be written as a sum of positive squares in 4 ways, for example, as 1087775991225 + 189890263696 = 1042965^2 + 435764^2 .

It is not a de Polignac number, because 1277666254921 - 2¹³ = 1277666246729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1277666254961) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 894097435 + ... + 894098863.

Almost surely, 2^{1277666254921} is an apocalyptic number.

1277666254921 is the 1130339-th square number.

1277666254921 is the 565170-th centered octagonal number.

It is an amenable number.

1277666254921 is a deficient number, since it is larger than the sum of its proper divisors (222917847980).

1277666254921 is an frugal number, since it uses more digits than its factorization.

1277666254921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3098 (or 1549 counting only the distinct ones).

The product of its digits is 15240960, while the sum is 58.

The spelling of 1277666254921 in words is "one trillion, two hundred seventy-seven billion, six hundred sixty-six million, two hundred fifty-four thousand, nine hundred twenty-one".