261520016505 has 32 divisors (see below), whose sum is σ = 480496112640. Its totient is φ = 120124025280.

The previous prime is 261520016447. The next prime is 261520016533. The reversal of 261520016505 is 505610025162.

It is not a de Polignac number, because 261520016505 - 2¹⁶ = 261519950969 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 41706597 + ... + 41712866.

It is an arithmetic number, because the mean of its divisors is an integer number (15015503520).

Almost surely, 2^261520016505 is an apocalyptic number.

It is an amenable number.

261520016505 is a deficient number, since it is larger than the sum of its proper divisors (218976096135).

261520016505 is a wasteful number, since it uses less digits than its factorization.

261520016505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83419501.

The product of its (nonzero) digits is 18000, while the sum is 33.

The spelling of 261520016505 in words is "two hundred sixty-one billion, five hundred twenty million, sixteen thousand, five hundred five".