261099221987 has 8 divisors (see below), whose sum is σ = 268173230640. Its totient is φ = 254058819840.

The previous prime is 261099221951. The next prime is 261099222011. The reversal of 261099221987 is 789122990162.

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

It is a cyclic number.

It is not a de Polignac number, because 261099221987 - 2¹⁴ = 261099205603 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261099221287) 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, 8385878 + ... + 8416955.

It is an arithmetic number, because the mean of its divisors is an integer number (33521653830).

Almost surely, 2^261099221987 is an apocalyptic number.

261099221987 is a deficient number, since it is larger than the sum of its proper divisors (7074008653).

261099221987 is a wasteful number, since it uses less digits than its factorization.

261099221987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16803253.

The product of its (nonzero) digits is 1959552, while the sum is 56.

The spelling of 261099221987 in words is "two hundred sixty-one billion, ninety-nine million, two hundred twenty-one thousand, nine hundred eighty-seven".