1257383211561 has 9 divisors (see below), whose sum is σ = 1816225053591. Its totient is φ = 838253231712.

The previous prime is 1257383211521. The next prime is 1257383211571. The reversal of 1257383211561 is 1651123837521.

The square root of 1257383211561 is 1121331.

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

1257383211561 is a `hidden beast` number, since 1 + 2 + 5 + 7 + 3 + 83 + 2 + 1 + 1 + 561 = 666.

It can be written as a sum of positive squares in only one way, i.e., 428088861225 + 829294350336 = 654285^2 + 910656^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 1257383211561 - 2⁷ = 1257383211433 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1257383211521) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3177105 + ... + 3550881.

Almost surely, 2^{1257383211561} is an apocalyptic number.

1257383211561 is the 1121331-st square number.

1257383211561 is the 560666-th centered octagonal number.

It is an amenable number.

1257383211561 is a deficient number, since it is larger than the sum of its proper divisors (558841842030).

1257383211561 is an frugal number, since it uses more digits than its factorization.

1257383211561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 747560 (or 373780 counting only the distinct ones).

The product of its digits is 302400, while the sum is 45.

It can be divided in two parts, 1257383 and 211561, that added together give a square (1468944 = 1212²).

The spelling of 1257383211561 in words is "one trillion, two hundred fifty-seven billion, three hundred eighty-three million, two hundred eleven thousand, five hundred sixty-one".