821447900 has 144 divisors (see below), whose sum is σ = 2309852160. Its totient is φ = 246240000.

The previous prime is 821447897. The next prime is 821447909. The reversal of 821447900 is 9744128.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821447909) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 170525 + ... + 175275.

It is an arithmetic number, because the mean of its divisors is an integer number (16040640).

Almost surely, 2^821447900 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821447900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1154926080).

821447900 is an abundant number, since it is smaller than the sum of its proper divisors (1488404260).

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

821447900 is a wasteful number, since it uses less digits than its factorization.

821447900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4804 (or 4797 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 35.

The square root of 821447900 is about 28660.9124069699. The cubic root of 821447900 is about 936.5407408856.

The spelling of 821447900 in words is "eight hundred twenty-one million, four hundred forty-seven thousand, nine hundred".