821512380 has 72 divisors (see below), whose sum is σ = 2490817392. Its totient is φ = 202215936.

The previous prime is 821512361. The next prime is 821512421. The reversal of 821512380 is 83215128.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30369 + ... + 50648.

It is an arithmetic number, because the mean of its divisors is an integer number (34594686).

Almost surely, 2^821512380 is an apocalyptic number.

It is an amenable number.

821512380 is an abundant number, since it is smaller than the sum of its proper divisors (1669305012).

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

821512380 is a wasteful number, since it uses less digits than its factorization.

821512380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81055 (or 81040 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 30.

The square root of 821512380 is about 28662.0372618556. The cubic root of 821512380 is about 936.5652450028.

The spelling of 821512380 in words is "eight hundred twenty-one million, five hundred twelve thousand, three hundred eighty".