261553320554531 has 4 divisors (see below), whose sum is σ = 261559679627064. Its totient is φ = 261546961482000.

The previous prime is 261553320554479. The next prime is 261553320554549. The reversal of 261553320554531 is 135455023355162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261553320554531 - 2¹⁰ = 261553320553507 is a prime.

It is a super-2 number, since 2×261553320554531² (a number of 30 digits) contains 22 as substring.

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 261553320554531.

It is not an unprimeable number, because it can be changed into a prime (261553320554831) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3179474570 + ... + 3179556831.

It is an arithmetic number, because the mean of its divisors is an integer number (65389919906766).

Almost surely, 2^{261553320554531} is an apocalyptic number.

261553320554531 is a deficient number, since it is larger than the sum of its proper divisors (6359072533).

261553320554531 is an equidigital number, since it uses as much as digits as its factorization.

261553320554531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6359072532.

The product of its (nonzero) digits is 8100000, while the sum is 50.

The spelling of 261553320554531 in words is "two hundred sixty-one trillion, five hundred fifty-three billion, three hundred twenty million, five hundred fifty-four thousand, five hundred thirty-one".