820690640 has 240 divisors, whose sum is σ = 2532587904. Its totient is φ = 240230400.

The previous prime is 820690597. The next prime is 820690679. The reversal of 820690640 is 46096028.

It is a hoax number, since the sum of its digits (35) coincides with the sum of the digits of its distinct prime factors.

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

It is a self number, because there is not a number n which added to its sum of digits gives 820690640.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1780010 + ... + 1780470.

Almost surely, 2^820690640 is an apocalyptic number.

820690640 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 820690640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1266293952).

820690640 is an abundant number, since it is smaller than the sum of its proper divisors (1711897264).

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

820690640 is a wasteful number, since it uses less digits than its factorization.

820690640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526 (or 503 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 820690640 is about 28647.6986859329. The cubic root of 820690640 is about 936.2528659101.

The spelling of 820690640 in words is "eight hundred twenty million, six hundred ninety thousand, six hundred forty".