261205615 has 8 divisors (see below), whose sum is σ = 341941968. Its totient is φ = 189967680.

The previous prime is 261205589. The next prime is 261205619. The reversal of 261205615 is 516502162.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 261205615 - 2⁵ = 261205583 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261205619) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2374542 + ... + 2374651.

It is an arithmetic number, because the mean of its divisors is an integer number (42742746).

Almost surely, 2^261205615 is an apocalyptic number.

261205615 is a deficient number, since it is larger than the sum of its proper divisors (80736353).

261205615 is a wasteful number, since it uses less digits than its factorization.

261205615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4749209.

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 261205615 is about 16161.8567930792. The cubic root of 261205615 is about 639.2354273029.

Adding to 261205615 its reverse (516502162), we get a palindrome (777707777).

The spelling of 261205615 in words is "two hundred sixty-one million, two hundred five thousand, six hundred fifteen".