261567217953 has 20 divisors (see below), whose sum is σ = 401296657300. Its totient is φ = 169665220512.

The previous prime is 261567217949. The next prime is 261567217981. The reversal of 261567217953 is 359712765162.

It is a happy number.

261567217953 is a `hidden beast` number, since 2 + 6 + 1 + 567 + 2 + 1 + 79 + 5 + 3 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 245310202944 + 16257015009 = 495288^2 + 127503^2 .

It is not a de Polignac number, because 261567217953 - 2² = 261567217949 is a prime.

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 261567217953.

It is not an unprimeable number, because it can be changed into a prime (261567217913) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 43635178 + ... + 43641171.

It is an arithmetic number, because the mean of its divisors is an integer number (20064832865).

Almost surely, 2^261567217953 is an apocalyptic number.

It is an amenable number.

261567217953 is a deficient number, since it is larger than the sum of its proper divisors (139729439347).

261567217953 is an equidigital number, since it uses as much as digits as its factorization.

261567217953 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87276398 (or 87276389 counting only the distinct ones).

The product of its digits is 4762800, while the sum is 54.

The spelling of 261567217953 in words is "two hundred sixty-one billion, five hundred sixty-seven million, two hundred seventeen thousand, nine hundred fifty-three".