899664821 has 4 divisors (see below), whose sum is σ = 981452544. Its totient is φ = 817877100.

The previous prime is 899664761. The next prime is 899664833. The reversal of 899664821 is 128466998.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 899664821 - 2¹⁴ = 899648437 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 (899664721) 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, 40893845 + ... + 40893866.

It is an arithmetic number, because the mean of its divisors is an integer number (245363136).

Almost surely, 2^899664821 is an apocalyptic number.

It is an amenable number.

899664821 is a deficient number, since it is larger than the sum of its proper divisors (81787723).

899664821 is a wasteful number, since it uses less digits than its factorization.

899664821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81787722.

The product of its digits is 1492992, while the sum is 53.

The square root of 899664821 is about 29994.4131631209. The cubic root of 899664821 is about 965.3695135138.

The spelling of 899664821 in words is "eight hundred ninety-nine million, six hundred sixty-four thousand, eight hundred twenty-one".