121912561 has 8 divisors (see below), whose sum is σ = 124626600. Its totient is φ = 119213952.

The previous prime is 121912547. The next prime is 121912577. The reversal of 121912561 is 165219121.

It can be written as a sum of positive squares in 4 ways, for example, as 7529536 + 114383025 = 2744^2 + 10695^2 .

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 121912561 - 2⁵ = 121912529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121915561) 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, 12915 + ... + 20263.

It is an arithmetic number, because the mean of its divisors is an integer number (15578325).

Almost surely, 2^121912561 is an apocalyptic number.

It is an amenable number.

121912561 is a deficient number, since it is larger than the sum of its proper divisors (2714039).

121912561 is an equidigital number, since it uses as much as digits as its factorization.

121912561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7715.

The product of its digits is 1080, while the sum is 28.

The square root of 121912561 is about 11041.4021301644. The cubic root of 121912561 is about 495.8490492457.

The spelling of 121912561 in words is "one hundred twenty-one million, nine hundred twelve thousand, five hundred sixty-one".