661102261 has 4 divisors (see below), whose sum is σ = 661414624. Its totient is φ = 660789900.

The previous prime is 661102259. The next prime is 661102279. The reversal of 661102261 is 162201166.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 661102261 - 2¹ = 661102259 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 (661102361) 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, 152985 + ... + 157246.

It is an arithmetic number, because the mean of its divisors is an integer number (165353656).

Almost surely, 2^661102261 is an apocalyptic number.

It is an amenable number.

661102261 is a deficient number, since it is larger than the sum of its proper divisors (312363).

661102261 is a wasteful number, since it uses less digits than its factorization.

661102261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 312362.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 661102261 is about 25711.9089334106. The cubic root of 661102261 is about 871.1431930779.

The spelling of 661102261 in words is "six hundred sixty-one million, one hundred two thousand, two hundred sixty-one".