121431551 has 2 divisors, whose sum is σ = 121431552. Its totient is φ = 121431550.

The previous prime is 121431523. The next prime is 121431553. The reversal of 121431551 is 155134121.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-121431551 is a prime.

Together with 121431553, 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 (121431553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60715775 + 60715776.

It is an arithmetic number, because the mean of its divisors is an integer number (60715776).

Almost surely, 2^121431551 is an apocalyptic number.

121431551 is a deficient number, since it is larger than the sum of its proper divisors (1).

121431551 is an equidigital number, since it uses as much as digits as its factorization.

121431551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 600, while the sum is 23.

The square root of 121431551 is about 11019.5984954081. The cubic root of 121431551 is about 495.1960601431.

Adding to 121431551 its reverse (155134121), we get a palindrome (276565672).

The spelling of 121431551 in words is "one hundred twenty-one million, four hundred thirty-one thousand, five hundred fifty-one".