55820978781 has 4 divisors (see below), whose sum is σ = 74427971712. Its totient is φ = 37213985852.

The previous prime is 55820978761. The next prime is 55820978791. The reversal of 55820978781 is 18787902855.

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.

It is a cyclic number.

It is not a de Polignac number, because 55820978781 - 2⁵ = 55820978749 is a prime.

It is a super-2 number, since 2×55820978781² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55820978701) 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, 9303496461 + ... + 9303496466.

It is an arithmetic number, because the mean of its divisors is an integer number (18606992928).

Almost surely, 2^55820978781 is an apocalyptic number.

It is an amenable number.

55820978781 is a deficient number, since it is larger than the sum of its proper divisors (18606992931).

55820978781 is a wasteful number, since it uses less digits than its factorization.

55820978781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18606992930.

The product of its (nonzero) digits is 11289600, while the sum is 60.

The spelling of 55820978781 in words is "fifty-five billion, eight hundred twenty million, nine hundred seventy-eight thousand, seven hundred eighty-one".