55239991 has 2 divisors, whose sum is σ = 55239992. Its totient is φ = 55239990.

The previous prime is 55239967. The next prime is 55240013. The reversal of 55239991 is 19993255.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 55239991 - 2²¹ = 53142839 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55239901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27619995 + 27619996.

It is an arithmetic number, because the mean of its divisors is an integer number (27619996).

Almost surely, 2^55239991 is an apocalyptic number.

55239991 is a deficient number, since it is larger than the sum of its proper divisors (1).

55239991 is an equidigital number, since it uses as much as digits as its factorization.

55239991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 109350, while the sum is 43.

The square root of 55239991 is about 7432.3610649645. The cubic root of 55239991 is about 380.8475794677.

The spelling of 55239991 in words is "fifty-five million, two hundred thirty-nine thousand, nine hundred ninety-one".