71001005661 has 6 divisors (see below), whose sum is σ = 102557008190. Its totient is φ = 47334003768.

The previous prime is 71001005623. The next prime is 71001005687. The reversal of 71001005661 is 16650010017.

It can be written as a sum of positive squares in only one way, i.e., 66455684100 + 4545321561 = 257790^2 + 67419^2 .

It is not a de Polignac number, because 71001005661 - 2¹⁵ = 71000972893 is a prime.

It is a super-2 number, since 2×71001005661² (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 (71001005161) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3944500306 + ... + 3944500323.

Almost surely, 2^71001005661 is an apocalyptic number.

It is an amenable number.

71001005661 is a deficient number, since it is larger than the sum of its proper divisors (31556002529).

71001005661 is a wasteful number, since it uses less digits than its factorization.

71001005661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7889000635 (or 7889000632 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

Adding to 71001005661 its reverse (16650010017), we get a palindrome (87651015678).

The spelling of 71001005661 in words is "seventy-one billion, one million, five thousand, six hundred sixty-one".