816889821 has 8 divisors (see below), whose sum is σ = 1188203424. Its totient is φ = 495084720.

The previous prime is 816889817. The next prime is 816889823. The reversal of 816889821 is 128988618.

It is a happy number.

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

It is not a de Polignac number, because 816889821 - 2² = 816889817 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816889823) 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, 12377086 + ... + 12377151.

It is an arithmetic number, because the mean of its divisors is an integer number (148525428).

Almost surely, 2^816889821 is an apocalyptic number.

It is an amenable number.

816889821 is a deficient number, since it is larger than the sum of its proper divisors (371313603).

816889821 is a wasteful number, since it uses less digits than its factorization.

816889821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24754251.

The product of its digits is 442368, while the sum is 51.

The square root of 816889821 is about 28581.2844532922. The cubic root of 816889821 is about 934.8052902722.

The spelling of 816889821 in words is "eight hundred sixteen million, eight hundred eighty-nine thousand, eight hundred twenty-one".