261342815 has 32 divisors (see below), whose sum is σ = 340804800. Its totient is φ = 191738880.

The previous prime is 261342811. The next prime is 261342833. The reversal of 261342815 is 518243162.

261342815 = 2937² + 2938² + ... + 2966².

It is not a de Polignac number, because 261342815 - 2² = 261342811 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261342811) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 891809 + ... + 892101.

It is an arithmetic number, because the mean of its divisors is an integer number (10650150).

Almost surely, 2^261342815 is an apocalyptic number.

261342815 is a deficient number, since it is larger than the sum of its proper divisors (79461985).

261342815 is a wasteful number, since it uses less digits than its factorization.

261342815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 587.

The product of its digits is 11520, while the sum is 32.

The square root of 261342815 is about 16166.1007976568. The cubic root of 261342815 is about 639.3473286105.

Adding to 261342815 its reverse (518243162), we get a palindrome (779585977).

The spelling of 261342815 in words is "two hundred sixty-one million, three hundred forty-two thousand, eight hundred fifteen".