261515771 has 4 divisors (see below), whose sum is σ = 285289944. Its totient is φ = 237741600.

The previous prime is 261515767. The next prime is 261515803. The reversal of 261515771 is 177515162.

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 261515771 - 2² = 261515767 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261515701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11887070 + ... + 11887091.

It is an arithmetic number, because the mean of its divisors is an integer number (71322486).

Almost surely, 2^261515771 is an apocalyptic number.

261515771 is a deficient number, since it is larger than the sum of its proper divisors (23774173).

261515771 is a wasteful number, since it uses less digits than its factorization.

261515771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23774172.

The product of its digits is 14700, while the sum is 35.

The square root of 261515771 is about 16171.4492547823. The cubic root of 261515771 is about 639.4883369790.

The spelling of 261515771 in words is "two hundred sixty-one million, five hundred fifteen thousand, seven hundred seventy-one".