71661081 has 8 divisors (see below), whose sum is σ = 96894144. Its totient is φ = 47101040.

The previous prime is 71661049. The next prime is 71661089. The reversal of 71661081 is 18016617.

It is a happy number.

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 71661081 - 2⁵ = 71661049 is a prime.

It is a super-2 number, since 2×71661081² = 10270621060177122, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (71661089) 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, 168006 + ... + 168431.

It is an arithmetic number, because the mean of its divisors is an integer number (12111768).

Almost surely, 2^71661081 is an apocalyptic number.

71661081 is a gapful number since it is divisible by the number (71) formed by its first and last digit.

It is an amenable number.

71661081 is a deficient number, since it is larger than the sum of its proper divisors (25233063).

71661081 is a wasteful number, since it uses less digits than its factorization.

71661081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336511.

The product of its (nonzero) digits is 2016, while the sum is 30.

The square root of 71661081 is about 8465.2868232565. The cubic root of 71661081 is about 415.3629785052.

Adding to 71661081 its reverse (18016617), we get a palindrome (89677698).

The spelling of 71661081 in words is "seventy-one million, six hundred sixty-one thousand, eighty-one".