71661421 has 8 divisors (see below), whose sum is σ = 77273784. Its totient is φ = 66063360.

The previous prime is 71661413. The next prime is 71661427. The reversal of 71661421 is 12416617.

It can be written as a sum of positive squares in 4 ways, for example, as 9030025 + 62631396 = 3005^2 + 7914^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 71661421 - 2³ = 71661413 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 71661421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71661427) 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, 8325 + ... + 14581.

It is an arithmetic number, because the mean of its divisors is an integer number (9659223).

Almost surely, 2^71661421 is an apocalyptic number.

It is an amenable number.

71661421 is a deficient number, since it is larger than the sum of its proper divisors (5612363).

71661421 is a wasteful number, since it uses less digits than its factorization.

71661421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7151.

The product of its digits is 2016, while the sum is 28.

The square root of 71661421 is about 8465.3069052457. The cubic root of 71661421 is about 415.3636354085.

The spelling of 71661421 in words is "seventy-one million, six hundred sixty-one thousand, four hundred twenty-one".