55420781 has 4 divisors (see below), whose sum is σ = 59683932. Its totient is φ = 51157632.

The previous prime is 55420759. The next prime is 55420789. The reversal of 55420781 is 18702455.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4583881 + 50836900 = 2141^2 + 7130^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55420781 is a prime.

It is a super-4 number, since 4×55420781⁴ (a number of 32 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55420789) 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, 2131556 + ... + 2131581.

It is an arithmetic number, because the mean of its divisors is an integer number (14920983).

Almost surely, 2^55420781 is an apocalyptic number.

It is an amenable number.

55420781 is a deficient number, since it is larger than the sum of its proper divisors (4263151).

55420781 is a wasteful number, since it uses less digits than its factorization.

55420781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4263150.

The product of its (nonzero) digits is 11200, while the sum is 32.

The square root of 55420781 is about 7444.5134830961. The cubic root of 55420781 is about 381.2626076275.

The spelling of 55420781 in words is "fifty-five million, four hundred twenty thousand, seven hundred eighty-one".