55611781 has 4 divisors (see below), whose sum is σ = 55683232.
Its totient is φ = 55540332.
The previous prime is 55611779. The next prime is 55611791. The reversal of 55611781 is 18711655.
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18711655 = 5 ⋅3742331.
It is a cyclic number.
It is not a de Polignac number, because 55611781 - 21 = 55611779 is a prime.
It is a super-2 number, since 2×556117812 = 6185340371983922, which contains 22 as substring.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (55611701) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34545 + ... + 36118.
It is an arithmetic number, because the mean of its divisors is an integer number (13920808).
Almost surely, 255611781 is an apocalyptic number.
It is an amenable number.
55611781 is a deficient number, since it is larger than the sum of its proper divisors (71451).
55611781 is an equidigital number, since it uses as much as digits as its factorization.
55611781 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 71450.
The product of its digits is 8400, while the sum is 34.
The square root of 55611781 is about 7457.3306886580.
The cubic root of 55611781 is about 381.7000949175.
The spelling of 55611781 in words is "fifty-five million, six hundred eleven thousand, seven hundred eighty-one".