71642605561 has 2 divisors, whose sum is σ = 71642605562. Its totient is φ = 71642605560.

The previous prime is 71642605519. The next prime is 71642605571. The reversal of 71642605561 is 16550624617.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51911065600 + 19731539961 = 227840^2 + 140469^2 .

It is a cyclic number.

It is not a de Polignac number, because 71642605561 - 2¹⁷ = 71642474489 is a prime.

It is not a weakly prime, because it can be changed into another prime (71642605571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35821302780 + 35821302781.

It is an arithmetic number, because the mean of its divisors is an integer number (35821302781).

Almost surely, 2^71642605561 is an apocalyptic number.

It is an amenable number.

71642605561 is a deficient number, since it is larger than the sum of its proper divisors (1).

71642605561 is an equidigital number, since it uses as much as digits as its factorization.

71642605561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 302400, while the sum is 43.

The spelling of 71642605561 in words is "seventy-one billion, six hundred forty-two million, six hundred five thousand, five hundred sixty-one".