71681399 has 4 divisors (see below), whose sum is σ = 71698536. Its totient is φ = 71664264.

The previous prime is 71681381. The next prime is 71681411. The reversal of 71681399 is 99318617.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 99318617 = 73 ⋅1360529.

It is a cyclic number.

It is not a de Polignac number, because 71681399 - 2²⁴ = 54904183 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 (71681329) 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, 2312 + ... + 12194.

It is an arithmetic number, because the mean of its divisors is an integer number (17924634).

Almost surely, 2^71681399 is an apocalyptic number.

71681399 is a deficient number, since it is larger than the sum of its proper divisors (17137).

71681399 is an equidigital number, since it uses as much as digits as its factorization.

71681399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17136.

The product of its digits is 81648, while the sum is 44.

The square root of 71681399 is about 8466.4868156751. The cubic root of 71681399 is about 415.4022306228.

The spelling of 71681399 in words is "seventy-one million, six hundred eighty-one thousand, three hundred ninety-nine".