1556458351561 has 3 divisors (see below), whose sum is σ = 1556459599143. Its totient is φ = 1556457103980.

The previous prime is 1556458351549. The next prime is 1556458351597. The reversal of 1556458351561 is 1651538546551.

The square root of 1556458351561 is 1247581.

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 can be written as a sum of positive squares in only one way, i.e., 1534796399161 + 21661952400 = 1238869^2 + 147180^2 .

It is not a de Polignac number, because 1556458351561 - 2¹³ = 1556458343369 is a prime.

It is a super-2 number, since 2×1556458351561² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1556458351501) 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, 623791 + ... + 1871371.

It is an arithmetic number, because the mean of its divisors is an integer number (518819866381).

Almost surely, 2^{1556458351561} is an apocalyptic number.

1556458351561 is the 1247581-st square number.

1556458351561 is the 623791-st centered octagonal number.

It is an amenable number.

1556458351561 is a deficient number, since it is larger than the sum of its proper divisors (1247582).

1556458351561 is an frugal number, since it uses more digits than its factorization.

1556458351561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2495162 (or 1247581 counting only the distinct ones).

The product of its digits is 10800000, while the sum is 55.

The spelling of 1556458351561 in words is "one trillion, five hundred fifty-six billion, four hundred fifty-eight million, three hundred fifty-one thousand, five hundred sixty-one".