121721447 has 2 divisors, whose sum is σ = 121721448. Its totient is φ = 121721446.

The previous prime is 121721437. The next prime is 121721449. The reversal of 121721447 is 744127121.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 121721447 - 2⁸ = 121721191 is a prime.

It is a super-2 number, since 2×121721447² = 29632221319547618, which contains 22 as substring.

Together with 121721449, 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 (121721449) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60860723 + 60860724.

It is an arithmetic number, because the mean of its divisors is an integer number (60860724).

Almost surely, 2^121721447 is an apocalyptic number.

121721447 is a deficient number, since it is larger than the sum of its proper divisors (1).

121721447 is an equidigital number, since it uses as much as digits as its factorization.

121721447 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3136, while the sum is 29.

The square root of 121721447 is about 11032.7443095542. The cubic root of 121721447 is about 495.5898108326.

Adding to 121721447 its reverse (744127121), we get a palindrome (865848568).

The spelling of 121721447 in words is "one hundred twenty-one million, seven hundred twenty-one thousand, four hundred forty-seven".