42991121 has 2 divisors, whose sum is σ = 42991122. Its totient is φ = 42991120.

The previous prime is 42991097. The next prime is 42991127. The reversal of 42991121 is 12119924.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 35760400 + 7230721 = 5980^2 + 2689^2 .

It is a cyclic number.

It is not a de Polignac number, because 42991121 - 2¹⁰ = 42990097 is a prime.

It is not a weakly prime, because it can be changed into another prime (42991127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21495560 + 21495561.

It is an arithmetic number, because the mean of its divisors is an integer number (21495561).

Almost surely, 2^42991121 is an apocalyptic number.

It is an amenable number.

42991121 is a deficient number, since it is larger than the sum of its proper divisors (1).

42991121 is an equidigital number, since it uses as much as digits as its factorization.

42991121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1296, while the sum is 29.

The square root of 42991121 is about 6556.7614719463. The cubic root of 42991121 is about 350.3156906800.

The spelling of 42991121 in words is "forty-two million, nine hundred ninety-one thousand, one hundred twenty-one".