820921764 has 24 divisors (see below), whose sum is σ = 2062829440. Its totient is φ = 252591264.

The previous prime is 820921753. The next prime is 820921769. The reversal of 820921764 is 467129028.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (820921769) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2631004 + ... + 2631315.

Almost surely, 2^820921764 is an apocalyptic number.

It is an amenable number.

820921764 is an abundant number, since it is smaller than the sum of its proper divisors (1241907676).

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

820921764 is a wasteful number, since it uses less digits than its factorization.

820921764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5262339 (or 5262337 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 39.

The square root of 820921764 is about 28651.7323036496. The cubic root of 820921764 is about 936.3407472572.

The spelling of 820921764 in words is "eight hundred twenty million, nine hundred twenty-one thousand, seven hundred sixty-four".