71721765 has 24 divisors (see below), whose sum is σ = 126966528. Its totient is φ = 37436640.

The previous prime is 71721763. The next prime is 71721781. The reversal of 71721765 is 56712717.

It is not a de Polignac number, because 71721765 - 2¹ = 71721763 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71721763) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14841 + ... + 19070.

It is an arithmetic number, because the mean of its divisors is an integer number (5290272).

Almost surely, 2^71721765 is an apocalyptic number.

It is an amenable number.

71721765 is a deficient number, since it is larger than the sum of its proper divisors (55244763).

71721765 is a wasteful number, since it uses less digits than its factorization.

71721765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33969 (or 33966 counting only the distinct ones).

The product of its digits is 20580, while the sum is 36.

The square root of 71721765 is about 8468.8703496984. The cubic root of 71721765 is about 415.4801912472.

The spelling of 71721765 in words is "seventy-one million, seven hundred twenty-one thousand, seven hundred sixty-five".