71661321 has 8 divisors (see below), whose sum is σ = 106164960. Its totient is φ = 47774196.

The previous prime is 71661313. The next prime is 71661329. The reversal of 71661321 is 12316617.

It is an interprime number because it is at equal distance from previous prime (71661313) and next prime (71661329).

It is not a de Polignac number, because 71661321 - 2³ = 71661313 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 2654123 = 71661321 / (7 + 1 + 6 + 6 + 1 + 3 + 2 + 1).

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 7 ways as a sum of consecutive naturals, for example, 1327035 + ... + 1327088.

It is an arithmetic number, because the mean of its divisors is an integer number (13270620).

Almost surely, 2^71661321 is an apocalyptic number.

It is an amenable number.

71661321 is a deficient number, since it is larger than the sum of its proper divisors (34503639).

71661321 is a wasteful number, since it uses less digits than its factorization.

71661321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2654132 (or 2654126 counting only the distinct ones).

The product of its digits is 1512, while the sum is 27.

The square root of 71661321 is about 8465.3009987832. The cubic root of 71661321 is about 415.3634422019.

Adding to 71661321 its reverse (12316617), we get a palindrome (83977938).

The spelling of 71661321 in words is "seventy-one million, six hundred sixty-one thousand, three hundred twenty-one".