75721721 has 8 divisors (see below), whose sum is σ = 79088640. Its totient is φ = 72424368.

The previous prime is 75721691. The next prime is 75721733. The reversal of 75721721 is 12712757.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-75721721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (75721771) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15161 + ... + 19526.

It is an arithmetic number, because the mean of its divisors is an integer number (9886080).

Almost surely, 2^75721721 is an apocalyptic number.

It is an amenable number.

75721721 is a deficient number, since it is larger than the sum of its proper divisors (3366919).

75721721 is a wasteful number, since it uses less digits than its factorization.

75721721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34783.

The product of its digits is 6860, while the sum is 32.

The square root of 75721721 is about 8701.8228550115. The cubic root of 75721721 is about 423.0647345817.

The spelling of 75721721 in words is "seventy-five million, seven hundred twenty-one thousand, seven hundred twenty-one".