820931440 has 80 divisors (see below), whose sum is σ = 2200805568. Its totient is φ = 278949888.

The previous prime is 820931431. The next prime is 820931459. The reversal of 820931440 is 44139028.

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

It is a congruent number.

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, 56794 + ... + 69766.

Almost surely, 2^820931440 is an apocalyptic number.

820931440 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 820931440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1100402784).

820931440 is an abundant number, since it is smaller than the sum of its proper divisors (1379874128).

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

820931440 is a wasteful number, since it uses less digits than its factorization.

820931440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13106 (or 13100 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 820931440 is about 28651.9011585619. The cubic root of 820931440 is about 936.3444260477.

The spelling of 820931440 in words is "eight hundred twenty million, nine hundred thirty-one thousand, four hundred forty".