6555978536781 has 4 divisors (see below), whose sum is σ = 8741304715712. Its totient is φ = 4370652357852.

The previous prime is 6555978536747. The next prime is 6555978536819. The reversal of 6555978536781 is 1876358795556.

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 not a de Polignac number, because 6555978536781 - 2⁶ = 6555978536717 is a prime.

It is a super-2 number, since 2×6555978536781² (a number of 26 digits) 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 (6555978536711) 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, 1092663089461 + ... + 1092663089466.

It is an arithmetic number, because the mean of its divisors is an integer number (2185326178928).

Almost surely, 2^{6555978536781} is an apocalyptic number.

It is an amenable number.

6555978536781 is a deficient number, since it is larger than the sum of its proper divisors (2185326178931).

6555978536781 is a wasteful number, since it uses less digits than its factorization.

6555978536781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2185326178930.

The product of its digits is 1905120000, while the sum is 75.

The spelling of 6555978536781 in words is "six trillion, five hundred fifty-five billion, nine hundred seventy-eight million, five hundred thirty-six thousand, seven hundred eighty-one".