804978721 has 8 divisors (see below), whose sum is σ = 812743784. Its totient is φ = 797247360.

The previous prime is 804978703. The next prime is 804978743. The reversal of 804978721 is 127879408.

It can be written as a sum of positive squares in 4 ways, for example, as 154728721 + 650250000 = 12439^2 + 25500^2 .

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

It is a 3-Lehmer number, since φ(804978721) divides (804978721-1)³.

It is a cyclic number.

It is a Carmichael number.

It is not a de Polignac number, because 804978721 - 2⁷ = 804978593 is a prime.

It is a deceptive number, since it divides R_804978720.

It is not an unprimeable number, because it can be changed into a prime (804978701) 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, 40951 + ... + 57331.

It is an arithmetic number, because the mean of its divisors is an integer number (101592973).

It is a Poulet number, since it divides 2^804978720-1.

Almost surely, 2^804978721 is an apocalyptic number.

804978721 is the 16381-st octagonal number.

It is an amenable number.

804978721 is a deficient number, since it is larger than the sum of its proper divisors (7765063).

804978721 is a wasteful number, since it uses less digits than its factorization.

804978721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16851.

The product of its (nonzero) digits is 225792, while the sum is 46.

The square root of 804978721 is about 28372.1469226423. The cubic root of 804978721 is about 930.2395501923.

The spelling of 804978721 in words is "eight hundred four million, nine hundred seventy-eight thousand, seven hundred twenty-one".