71128661 has 4 divisors (see below), whose sum is σ = 71163852. Its totient is φ = 71093472.

The previous prime is 71128657. The next prime is 71128667. The reversal of 71128661 is 16682117.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16682117 = 17 ⋅981301.

It can be written as a sum of positive squares in 2 ways, for example, as 1739761 + 69388900 = 1319^2 + 8330^2 .

It is a cyclic number.

It is not a de Polignac number, because 71128661 - 2² = 71128657 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71128667) 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, 14366 + ... + 18671.

It is an arithmetic number, because the mean of its divisors is an integer number (17790963).

Almost surely, 2^71128661 is an apocalyptic number.

It is an amenable number.

71128661 is a deficient number, since it is larger than the sum of its proper divisors (35191).

71128661 is a wasteful number, since it uses less digits than its factorization.

71128661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35190.

The product of its digits is 4032, while the sum is 32.

The square root of 71128661 is about 8433.7809433255. The cubic root of 71128661 is about 414.3317468979.

The spelling of 71128661 in words is "seventy-one million, one hundred twenty-eight thousand, six hundred sixty-one".