55999987 has 2 divisors, whose sum is σ = 55999988. Its totient is φ = 55999986.

The previous prime is 55999969. The next prime is 55999991. The reversal of 55999987 is 78999955.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55999987 is a prime.

It is not a weakly prime, because it can be changed into another prime (55999997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27999993 + 27999994.

It is an arithmetic number, because the mean of its divisors is an integer number (27999994).

Almost surely, 2^55999987 is an apocalyptic number.

55999987 is a deficient number, since it is larger than the sum of its proper divisors (1).

55999987 is an equidigital number, since it uses as much as digits as its factorization.

55999987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9185400, while the sum is 61.

The square root of 55999987 is about 7483.3139049488. The cubic root of 55999987 is about 382.5862069496.

The spelling of 55999987 in words is "fifty-five million, nine hundred ninety-nine thousand, nine hundred eighty-seven".