55561993 has 2 divisors, whose sum is σ = 55561994. Its totient is φ = 55561992.

The previous prime is 55561981. The next prime is 55562021. The reversal of 55561993 is 39916555.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50239744 + 5322249 = 7088^2 + 2307^2 .

It is a cyclic number.

It is not a de Polignac number, because 55561993 - 2⁹ = 55561481 is a prime.

It is a super-2 number, since 2×55561993² = 6174270132264098, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (55561963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27780996 + 27780997.

It is an arithmetic number, because the mean of its divisors is an integer number (27780997).

Almost surely, 2^55561993 is an apocalyptic number.

It is an amenable number.

55561993 is a deficient number, since it is larger than the sum of its proper divisors (1).

55561993 is an equidigital number, since it uses as much as digits as its factorization.

55561993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 182250, while the sum is 43.

The square root of 55561993 is about 7453.9917493917. The cubic root of 55561993 is about 381.5861516839.

The spelling of 55561993 in words is "fifty-five million, five hundred sixty-one thousand, nine hundred ninety-three".