261215015 has 4 divisors (see below), whose sum is σ = 313458024. Its totient is φ = 208972008.

The previous prime is 261215011. The next prime is 261215039. The reversal of 261215015 is 510512162.

It is a happy number.

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 261215015 - 2² = 261215011 is a prime.

It is a super-2 number, since 2×261215015² = 136466568122900450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261215011) 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, 26121497 + ... + 26121506.

It is an arithmetic number, because the mean of its divisors is an integer number (78364506).

Almost surely, 2^261215015 is an apocalyptic number.

261215015 is a deficient number, since it is larger than the sum of its proper divisors (52243009).

261215015 is an equidigital number, since it uses as much as digits as its factorization.

261215015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52243008.

The product of its (nonzero) digits is 600, while the sum is 23.

The square root of 261215015 is about 16162.1475986330. The cubic root of 261215015 is about 639.2430952608.

Adding to 261215015 its reverse (510512162), we get a palindrome (771727177).

The spelling of 261215015 in words is "two hundred sixty-one million, two hundred fifteen thousand, fifteen".