78127721 has 8 divisors (see below), whose sum is σ = 89556480. Its totient is φ = 66765888.

The previous prime is 78127691. The next prime is 78127723. The reversal of 78127721 is 12772187.

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

It is not a de Polignac number, because 78127721 - 2¹⁸ = 77865577 is a prime.

It is a super-2 number, since 2×78127721² = 12207881577307682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78127723) 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, 14201 + ... + 18918.

It is an arithmetic number, because the mean of its divisors is an integer number (11194560).

Almost surely, 2^78127721 is an apocalyptic number.

It is an amenable number.

78127721 is a deficient number, since it is larger than the sum of its proper divisors (11428759).

78127721 is a wasteful number, since it uses less digits than its factorization.

78127721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33463.

The product of its digits is 10976, while the sum is 35.

The square root of 78127721 is about 8838.9886864958. The cubic root of 78127721 is about 427.4989496457.

The spelling of 78127721 in words is "seventy-eight million, one hundred twenty-seven thousand, seven hundred twenty-one".