864007821 has 12 divisors (see below), whose sum is σ = 1248696540. Its totient is φ = 575688960.

The previous prime is 864007799. The next prime is 864007861. The reversal of 864007821 is 128700468.

864007821 is a `hidden beast` number, since 8 + 640 + 0 + 7 + 8 + 2 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 690953796 + 173054025 = 26286^2 + 13155^2 .

It is not a de Polignac number, because 864007821 - 2¹⁴ = 863991437 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (864007861) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8410 + ... + 42411.

It is an arithmetic number, because the mean of its divisors is an integer number (104058045).

Almost surely, 2^864007821 is an apocalyptic number.

It is an amenable number.

864007821 is a deficient number, since it is larger than the sum of its proper divisors (384688719).

864007821 is a wasteful number, since it uses less digits than its factorization.

864007821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52716 (or 52713 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 864007821 is about 29394.0099510087. The cubic root of 864007821 is about 952.4435050296.

The spelling of 864007821 in words is "eight hundred sixty-four million, seven thousand, eight hundred twenty-one".