55645781 has 2 divisors, whose sum is σ = 55645782. Its totient is φ = 55645780.

The previous prime is 55645771. The next prime is 55645801. The reversal of 55645781 is 18754655.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 35700625 + 19945156 = 5975^2 + 4466^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55645781 is a prime.

It is a super-2 number, since 2×55645781² = 6192905886199922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55645721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27822890 + 27822891.

It is an arithmetic number, because the mean of its divisors is an integer number (27822891).

Almost surely, 2^55645781 is an apocalyptic number.

It is an amenable number.

55645781 is a deficient number, since it is larger than the sum of its proper divisors (1).

55645781 is an equidigital number, since it uses as much as digits as its factorization.

55645781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 168000, while the sum is 41.

The square root of 55645781 is about 7459.6099763996. The cubic root of 55645781 is about 381.7778671635. Note that the first 3 decimals are identical.

The spelling of 55645781 in words is "fifty-five million, six hundred forty-five thousand, seven hundred eighty-one".