261553242370253 has 4 divisors (see below), whose sum is σ = 276938727215580. Its totient is φ = 246167757524928.

The previous prime is 261553242370201. The next prime is 261553242370267. The reversal of 261553242370253 is 352073242355162.

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

It can be written as a sum of positive squares in 2 ways, for example, as 101219958220969 + 160333284149284 = 10060813^2 + 12662278^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261553242370253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261553242370753) 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, 7692742422638 + ... + 7692742422671.

It is an arithmetic number, because the mean of its divisors is an integer number (69234681803895).

Almost surely, 2^{261553242370253} is an apocalyptic number.

It is an amenable number.

261553242370253 is a deficient number, since it is larger than the sum of its proper divisors (15385484845327).

261553242370253 is a wasteful number, since it uses less digits than its factorization.

261553242370253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15385484845326.

The product of its (nonzero) digits is 9072000, while the sum is 50.

The spelling of 261553242370253 in words is "two hundred sixty-one trillion, five hundred fifty-three billion, two hundred forty-two million, three hundred seventy thousand, two hundred fifty-three".