55005991 has 2 divisors, whose sum is σ = 55005992.
Its totient is φ = 55005990.
The previous prime is 55005971. The next prime is 55006037. The reversal of 55005991 is 19950055.
It is a weak prime.
It is a cyclic number.
It is not a de Polignac number, because 55005991 - 211 = 55003943 is a prime.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (55005961) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27502995 + 27502996.
It is an arithmetic number, because the mean of its divisors is an integer number (27502996).
Almost surely, 255005991 is an apocalyptic number.
55005991 is a deficient number, since it is larger than the sum of its proper divisors (1).
55005991 is an equidigital number, since it uses as much as digits as its factorization.
55005991 is an evil number, because the sum of its binary digits is even.
The product of its (nonzero) digits is 10125, while the sum is 34.
The square root of 55005991 is about 7416.6023892346.
The cubic root of 55005991 is about 380.3090537495.
The spelling of 55005991 in words is "fifty-five million, five thousand, nine hundred ninety-one".