121931309 has 2 divisors, whose sum is σ = 121931310. Its totient is φ = 121931308.

The previous prime is 121931291. The next prime is 121931311. The reversal of 121931309 is 903139121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 99102025 + 22829284 = 9955^2 + 4778^2 .

It is a cyclic number.

It is not a de Polignac number, because 121931309 - 2¹⁶ = 121865773 is a prime.

It is a super-2 number, since 2×121931309² = 29734488228906962, which contains 22 as substring.

Together with 121931311, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121933309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60965654 + 60965655.

It is an arithmetic number, because the mean of its divisors is an integer number (60965655).

Almost surely, 2^121931309 is an apocalyptic number.

It is an amenable number.

121931309 is a deficient number, since it is larger than the sum of its proper divisors (1).

121931309 is an equidigital number, since it uses as much as digits as its factorization.

121931309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1458, while the sum is 29.

The square root of 121931309 is about 11042.2510839049. The cubic root of 121931309 is about 495.8744655534.

The spelling of 121931309 in words is "one hundred twenty-one million, nine hundred thirty-one thousand, three hundred nine".