1561546261 has 24 divisors (see below), whose sum is σ = 1796333112. Its totient is φ = 1354953600.

The previous prime is 1561546253. The next prime is 1561546277. The reversal of 1561546261 is 1626451651.

It can be written as a sum of positive squares in 4 ways, for example, as 494217361 + 1067328900 = 22231^2 + 32670^2 .

It is not a de Polignac number, because 1561546261 - 2³ = 1561546253 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1561546261.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561546201) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 233991 + ... + 240571.

It is an arithmetic number, because the mean of its divisors is an integer number (74847213).

Almost surely, 2^1561546261 is an apocalyptic number.

1561546261 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1561546261 is a deficient number, since it is larger than the sum of its proper divisors (234786851).

1561546261 is a wasteful number, since it uses less digits than its factorization.

1561546261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6693 (or 6682 counting only the distinct ones).

The product of its digits is 43200, while the sum is 37.

The square root of 1561546261 is about 39516.4049604718. The cubic root of 1561546261 is about 1160.1610609202.

The spelling of 1561546261 in words is "one billion, five hundred sixty-one million, five hundred forty-six thousand, two hundred sixty-one".