261561451 has 8 divisors (see below), whose sum is σ = 273142944. Its totient is φ = 249997440.

The previous prime is 261561449. The next prime is 261561457. The reversal of 261561451 is 154165162.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 261561451 - 2¹ = 261561449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261561457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33171 + ... + 40291.

It is an arithmetic number, because the mean of its divisors is an integer number (34142868).

Almost surely, 2^261561451 is an apocalyptic number.

261561451 is a deficient number, since it is larger than the sum of its proper divisors (11581493).

261561451 is a wasteful number, since it uses less digits than its factorization.

261561451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8741.

The product of its digits is 7200, while the sum is 31.

The square root of 261561451 is about 16172.8615587966. The cubic root of 261561451 is about 639.5255688018.

The spelling of 261561451 in words is "two hundred sixty-one million, five hundred sixty-one thousand, four hundred fifty-one".