878575721 has 4 divisors (see below), whose sum is σ = 878726100. Its totient is φ = 878425344.

The previous prime is 878575717. The next prime is 878575723. The reversal of 878575721 is 127575878.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 127575878 = 2 ⋅63787939.

It can be written as a sum of positive squares in 2 ways, for example, as 116208400 + 762367321 = 10780^2 + 27611^2 .

It is a cyclic number.

It is not a de Polignac number, because 878575721 - 2² = 878575717 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 878575721.

It is not an unprimeable number, because it can be changed into a prime (878575723) 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, 66056 + ... + 78233.

It is an arithmetic number, because the mean of its divisors is an integer number (219681525).

Almost surely, 2^878575721 is an apocalyptic number.

It is an amenable number.

878575721 is a deficient number, since it is larger than the sum of its proper divisors (150379).

878575721 is a wasteful number, since it uses less digits than its factorization.

878575721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150378.

The product of its digits is 1097600, while the sum is 50.

The square root of 878575721 is about 29640.7780093573. The cubic root of 878575721 is about 957.7666984039.

The spelling of 878575721 in words is "eight hundred seventy-eight million, five hundred seventy-five thousand, seven hundred twenty-one".