71979521 has 4 divisors (see below), whose sum is σ = 72266544. Its totient is φ = 71692500.

The previous prime is 71979491. The next prime is 71979539. The reversal of 71979521 is 12597917.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71979521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71979571) 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, 143135 + ... + 143636.

It is an arithmetic number, because the mean of its divisors is an integer number (18066636).

Almost surely, 2^71979521 is an apocalyptic number.

It is an amenable number.

71979521 is a deficient number, since it is larger than the sum of its proper divisors (287023).

71979521 is a wasteful number, since it uses less digits than its factorization.

71979521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 287022.

The product of its digits is 39690, while the sum is 41.

The square root of 71979521 is about 8484.0745517705. The cubic root of 71979521 is about 415.9773182437.

The spelling of 71979521 in words is "seventy-one million, nine hundred seventy-nine thousand, five hundred twenty-one".