857779621 has 16 divisors (see below), whose sum is σ = 898625520. Its totient is φ = 817966080.

The previous prime is 857779619. The next prime is 857779631. The reversal of 857779621 is 126977758.

It can be written as a sum of positive squares in 8 ways, for example, as 2217121 + 855562500 = 1489^2 + 29250^2 .

It is not a de Polignac number, because 857779621 - 2¹ = 857779619 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (857779631) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 877485 + ... + 878461.

It is an arithmetic number, because the mean of its divisors is an integer number (56164095).

Almost surely, 2^857779621 is an apocalyptic number.

It is an amenable number.

857779621 is a deficient number, since it is larger than the sum of its proper divisors (40845899).

857779621 is a wasteful number, since it uses less digits than its factorization.

857779621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1464.

The product of its digits is 1481760, while the sum is 52.

The square root of 857779621 is about 29287.8749826613. The cubic root of 857779621 is about 950.1494210030.

The spelling of 857779621 in words is "eight hundred fifty-seven million, seven hundred seventy-nine thousand, six hundred twenty-one".