1561761 has 12 divisors (see below), whose sum is σ = 2339792. Its totient is φ = 1041012.

The previous prime is 1561759. The next prime is 1561801. The reversal of 1561761 is 1671651.

It is not a de Polignac number, because 1561761 - 2¹ = 1561759 is a prime.

It is a super-2 number, since 2×1561761² = 4878194842242, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1561711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2971 + ... + 3456.

2^1561761 is an apocalyptic number.

It is an amenable number.

1561761 is a deficient number, since it is larger than the sum of its proper divisors (778031).

1561761 is an frugal number, since it uses more digits than its factorization.

1561761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6442 (or 6430 counting only the distinct ones).

The product of its digits is 1260, while the sum is 27.

The square root of 1561761 is about 1249.7043650400. The cubic root of 1561761 is about 116.0214239067.

It can be divided in two parts, 15 and 61761, that added together give a triangular number (61776 = T₃₅₁).

The spelling of 1561761 in words is "one million, five hundred sixty-one thousand, seven hundred sixty-one".