71661389 has 4 divisors (see below), whose sum is σ = 71678880. Its totient is φ = 71643900.

The previous prime is 71661379. The next prime is 71661413. The reversal of 71661389 is 98316617.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 98316617 = 7 ⋅14045231.

It is a cyclic number.

It is not a de Polignac number, because 71661389 - 2¹² = 71657293 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71661329) 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, 1082 + ... + 12020.

It is an arithmetic number, because the mean of its divisors is an integer number (17919720).

Almost surely, 2^71661389 is an apocalyptic number.

It is an amenable number.

71661389 is a deficient number, since it is larger than the sum of its proper divisors (17491).

71661389 is a wasteful number, since it uses less digits than its factorization.

71661389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17490.

The product of its digits is 54432, while the sum is 41.

The square root of 71661389 is about 8465.3050151781. The cubic root of 71661389 is about 415.3635735824.

The spelling of 71661389 in words is "seventy-one million, six hundred sixty-one thousand, three hundred eighty-nine".