6428555191781 has 4 divisors (see below), whose sum is σ = 6602299926732. Its totient is φ = 6254810456832.

The previous prime is 6428555191727. The next prime is 6428555191819. The reversal of 6428555191781 is 1871915558246.

It is a happy number.

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 4574080464100 + 1854474727681 = 2138710^2 + 1361791^2 .

It is a cyclic number.

It is not a de Polignac number, because 6428555191781 - 2³⁸ = 6153677284837 is a prime.

It is a super-2 number, since 2×6428555191781² (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 (6428555091781) 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, 86872367420 + ... + 86872367493.

It is an arithmetic number, because the mean of its divisors is an integer number (1650574981683).

Almost surely, 2^{6428555191781} is an apocalyptic number.

It is an amenable number.

6428555191781 is a deficient number, since it is larger than the sum of its proper divisors (173744734951).

6428555191781 is a wasteful number, since it uses less digits than its factorization.

6428555191781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173744734950.

The product of its digits is 24192000, while the sum is 62.

The spelling of 6428555191781 in words is "six trillion, four hundred twenty-eight billion, five hundred fifty-five million, one hundred ninety-one thousand, seven hundred eighty-one".