72126306781 has 4 divisors (see below), whose sum is σ = 72869877052. Its totient is φ = 71382736512.

The previous prime is 72126306773. The next prime is 72126306799. The reversal of 72126306781 is 18760362127.

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 49599298681 + 22527008100 = 222709^2 + 150090^2 .

It is a cyclic number.

It is not a de Polignac number, because 72126306781 - 2³ = 72126306773 is a prime.

It is a super-2 number, since 2×72126306781² (a number of 23 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 (72126306481) 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, 371784990 + ... + 371785183.

It is an arithmetic number, because the mean of its divisors is an integer number (18217469263).

Almost surely, 2^72126306781 is an apocalyptic number.

It is an amenable number.

72126306781 is a deficient number, since it is larger than the sum of its proper divisors (743570271).

72126306781 is an equidigital number, since it uses as much as digits as its factorization.

72126306781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 743570270.

The product of its (nonzero) digits is 169344, while the sum is 43.

The spelling of 72126306781 in words is "seventy-two billion, one hundred twenty-six million, three hundred six thousand, seven hundred eighty-one".