71506391261 has 2 divisors, whose sum is σ = 71506391262. Its totient is φ = 71506391260.

The previous prime is 71506391251. The next prime is 71506391279. The reversal of 71506391261 is 16219360517.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62485000900 + 9021390361 = 249970^2 + 94981^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71506391261 is a prime.

It is a super-2 number, since 2×71506391261² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71506391251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35753195630 + 35753195631.

It is an arithmetic number, because the mean of its divisors is an integer number (35753195631).

Almost surely, 2^71506391261 is an apocalyptic number.

It is an amenable number.

71506391261 is a deficient number, since it is larger than the sum of its proper divisors (1).

71506391261 is an equidigital number, since it uses as much as digits as its factorization.

71506391261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 68040, while the sum is 41.

The spelling of 71506391261 in words is "seventy-one billion, five hundred six million, three hundred ninety-one thousand, two hundred sixty-one".