71720640 has 140 divisors (see below), whose sum is σ = 255215136. Its totient is φ = 19118592.

The previous prime is 71720633. The next prime is 71720641. The reversal of 71720640 is 4602717.

71720640 is a `hidden beast` number, since 7 + 17 + 2 + 0 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (71720641) 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 19 ways as a sum of consecutive naturals, for example, 24537 + ... + 27303.

Almost surely, 2^71720640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 71720640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (127607568).

71720640 is an abundant number, since it is smaller than the sum of its proper divisors (183494496).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

71720640 is a wasteful number, since it uses less digits than its factorization.

71720640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2796 (or 2777 counting only the distinct ones).

The product of its (nonzero) digits is 2352, while the sum is 27.

The square root of 71720640 is about 8468.8039297176. The cubic root of 71720640 is about 415.4780188817.

The spelling of 71720640 in words is "seventy-one million, seven hundred twenty thousand, six hundred forty".