55135781 has 2 divisors, whose sum is σ = 55135782. Its totient is φ = 55135780.

The previous prime is 55135733. The next prime is 55135793. The reversal of 55135781 is 18753155.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 48427681 + 6708100 = 6959^2 + 2590^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55135781 is a prime.

It is a super-2 number, since 2×55135781² = 6079908692959922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55135721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27567890 + 27567891.

It is an arithmetic number, because the mean of its divisors is an integer number (27567891).

Almost surely, 2^55135781 is an apocalyptic number.

It is an amenable number.

55135781 is a deficient number, since it is larger than the sum of its proper divisors (1).

55135781 is an equidigital number, since it uses as much as digits as its factorization.

55135781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21000, while the sum is 35.

The square root of 55135781 is about 7425.3471972696. The cubic root of 55135781 is about 380.6079396169.

The spelling of 55135781 in words is "fifty-five million, one hundred thirty-five thousand, seven hundred eighty-one".