121257606991 has 4 divisors (see below), whose sum is σ = 121271132584. Its totient is φ = 121244081400.

The previous prime is 121257606983. The next prime is 121257607001. The reversal of 121257606991 is 199606752121.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 121257606991 - 2³ = 121257606983 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 (121257606931) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6749340 + ... + 6767281.

It is an arithmetic number, because the mean of its divisors is an integer number (30317783146).

Almost surely, 2^121257606991 is an apocalyptic number.

121257606991 is a deficient number, since it is larger than the sum of its proper divisors (13525593).

121257606991 is an equidigital number, since it uses as much as digits as its factorization.

121257606991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13525592.

The product of its (nonzero) digits is 408240, while the sum is 49.

The spelling of 121257606991 in words is "one hundred twenty-one billion, two hundred fifty-seven million, six hundred six thousand, nine hundred ninety-one".