961221665 has 8 divisors (see below), whose sum is σ = 1157106600. Its totient is φ = 766550272.

The previous prime is 961221661. The next prime is 961221689. The reversal of 961221665 is 566122169.

It can be written as a sum of positive squares in 4 ways, for example, as 31764496 + 929457169 = 5636^2 + 30487^2 .

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 961221665 - 2² = 961221661 is a prime.

It is not an unprimeable number, because it can be changed into a prime (961221661) 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, 301640 + ... + 304809.

It is an arithmetic number, because the mean of its divisors is an integer number (144638325).

Almost surely, 2^961221665 is an apocalyptic number.

It is an amenable number.

961221665 is a deficient number, since it is larger than the sum of its proper divisors (195884935).

961221665 is a wasteful number, since it uses less digits than its factorization.

961221665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 606771.

The product of its digits is 38880, while the sum is 38.

The square root of 961221665 is about 31003.5750357922. The cubic root of 961221665 is about 986.9031085993.

The spelling of 961221665 in words is "nine hundred sixty-one million, two hundred twenty-one thousand, six hundred sixty-five".