821407920 has 80 divisors (see below), whose sum is σ = 2555273952. Its totient is φ = 218275840.

The previous prime is 821407907. The next prime is 821407949. The reversal of 821407920 is 29704128.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 64480 + ... + 76160.

Almost surely, 2^821407920 is an apocalyptic number.

821407920 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821407920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1277636976).

821407920 is an abundant number, since it is smaller than the sum of its proper divisors (1733866032).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

821407920 is a wasteful number, since it uses less digits than its factorization.

821407920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11990 (or 11984 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 821407920 is about 28660.2149328996. The cubic root of 821407920 is about 936.5255467768.

The spelling of 821407920 in words is "eight hundred twenty-one million, four hundred seven thousand, nine hundred twenty".