71911921 has 4 divisors (see below), whose sum is σ = 76142052. Its totient is φ = 67681792.

The previous prime is 71911913. The next prime is 71911951. The reversal of 71911921 is 12911917.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 55711296 + 16200625 = 7464^2 + 4025^2 .

It is a cyclic number.

It is not a de Polignac number, because 71911921 - 2³ = 71911913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71911901) 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, 2115040 + ... + 2115073.

It is an arithmetic number, because the mean of its divisors is an integer number (19035513).

Almost surely, 2^71911921 is an apocalyptic number.

It is an amenable number.

71911921 is a deficient number, since it is larger than the sum of its proper divisors (4230131).

71911921 is a wasteful number, since it uses less digits than its factorization.

71911921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4230130.

The product of its digits is 1134, while the sum is 31.

The square root of 71911921 is about 8480.0896811296. The cubic root of 71911921 is about 415.8470549227.

The spelling of 71911921 in words is "seventy-one million, nine hundred eleven thousand, nine hundred twenty-one".