921320820 has 144 divisors (see below), whose sum is σ = 3246542208. Its totient is φ = 207118080.

The previous prime is 921320801. The next prime is 921320839. The reversal of 921320820 is 28023129.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (921320801) and next prime (921320839).

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, 70867 + ... + 82853.

It is an arithmetic number, because the mean of its divisors is an integer number (22545432).

Almost surely, 2^921320820 is an apocalyptic number.

921320820 is a gapful number since it is divisible by the number (90) 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 921320820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1623271104).

921320820 is an abundant number, since it is smaller than the sum of its proper divisors (2325221388).

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

921320820 is a wasteful number, since it uses less digits than its factorization.

921320820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12070 (or 12065 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 921320820 is about 30353.2670399745. The cubic root of 921320820 is about 973.0540437916.

Adding to 921320820 its reverse (28023129), we get a palindrome (949343949).

The spelling of 921320820 in words is "nine hundred twenty-one million, three hundred twenty thousand, eight hundred twenty".