821473947904 has 81 divisors (see below), whose sum is σ = 1686355520661. Its totient is φ = 399374945280.

The previous prime is 821473947901. The next prime is 821473947949. The reversal of 821473947904 is 409749374128.

It is a happy number.

The square root of 821473947904 is 906352.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 735066169600 + 86407778304 = 857360^2 + 293952^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (821473947901) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 536559619 + ... + 536561149.

Almost surely, 2^821473947904 is an apocalyptic number.

821473947904 is the 906352-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821473947904

821473947904 is an abundant number, since it is smaller than the sum of its proper divisors (864881572757).

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

821473947904 is an frugal number, since it uses more digits than its factorization.

With its predecessor (821473947903) it forms a Ruth-Aaron pair, since the sum of their distinct prime factors is the same (1570).

821473947904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3152 (or 1570 counting only the distinct ones).

The product of its (nonzero) digits is 12192768, while the sum is 58.

The spelling of 821473947904 in words is "eight hundred twenty-one billion, four hundred seventy-three million, nine hundred forty-seven thousand, nine hundred four".