1561632620409 has 81 divisors (see below), whose sum is σ = 2429396519277. Its totient is φ = 966451638528.

The previous prime is 1561632620363. The next prime is 1561632620423. The reversal of 1561632620409 is 9040262361651.

The square root of 1561632620409 is 1249653.

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

1561632620409 is a `hidden beast` number, since 1 + 5 + 6 + 1 + 632 + 6 + 2 + 0 + 4 + 0 + 9 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 828163701225 + 733468919184 = 910035^2 + 856428^2 .

It is not a de Polignac number, because 1561632620409 - 2¹¹ = 1561632618361 is a prime.

It is a super-2 number, since 2×1561632620409² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1561632620609) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 6819356307 + ... + 6819356535.

Almost surely, 2^{1561632620409} is an apocalyptic number.

1561632620409 is the 1249653-rd square number.

1561632620409 is the 624827-th centered octagonal number.

It is an amenable number.

1561632620409 is a deficient number, since it is larger than the sum of its proper divisors (867763898868).

1561632620409 is an equidigital number, since it uses as much as digits as its factorization.

1561632620409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 712 (or 356 counting only the distinct ones).

The product of its (nonzero) digits is 466560, while the sum is 45.

The spelling of 1561632620409 in words is "one trillion, five hundred sixty-one billion, six hundred thirty-two million, six hundred twenty thousand, four hundred nine".