121251791 has 4 divisors (see below), whose sum is σ = 126523632. Its totient is φ = 115979952.

The previous prime is 121251763. The next prime is 121251811. The reversal of 121251791 is 197152121.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 197152121 = 29 ⋅6798349.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-121251791 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 (121251751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2635886 + ... + 2635931.

It is an arithmetic number, because the mean of its divisors is an integer number (31630908).

Almost surely, 2^121251791 is an apocalyptic number.

121251791 is a deficient number, since it is larger than the sum of its proper divisors (5271841).

121251791 is an equidigital number, since it uses as much as digits as its factorization.

121251791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5271840.

The product of its digits is 1260, while the sum is 29.

The square root of 121251791 is about 11011.4390975930. The cubic root of 121251791 is about 494.9515865993.

The spelling of 121251791 in words is "one hundred twenty-one million, two hundred fifty-one thousand, seven hundred ninety-one".