121557379865 has 16 divisors (see below), whose sum is σ = 154666955520. Its totient is φ = 91455223680.

The previous prime is 121557379859. The next prime is 121557379901. The reversal of 121557379865 is 568973755121.

It is not a de Polignac number, because 121557379865 - 2¹⁴ = 121557363481 is a prime.

It is a super-3 number, since 3×121557379865³ (a number of 34 digits) contains 333 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4656881 + ... + 4682910.

It is an arithmetic number, because the mean of its divisors is an integer number (9666684720).

Almost surely, 2^121557379865 is an apocalyptic number.

It is an amenable number.

121557379865 is a deficient number, since it is larger than the sum of its proper divisors (33109575655).

121557379865 is a wasteful number, since it uses less digits than its factorization.

121557379865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9339952.

The product of its digits is 15876000, while the sum is 59.

The spelling of 121557379865 in words is "one hundred twenty-one billion, five hundred fifty-seven million, three hundred seventy-nine thousand, eight hundred sixty-five".