3972121920 has 252 divisors, whose sum is σ = 14796057276. Its totient is φ = 977633280.

The previous prime is 3972121903. The next prime is 3972121921. The reversal of 3972121920 is 291212793.

It can be written as a sum of positive squares in 6 ways, for example, as 1006665984 + 2965455936 = 31728^2 + 54456^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3972121921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 482640 + ... + 490800.

It is an arithmetic number, because the mean of its divisors is an integer number (58714513).

Almost surely, 2^3972121920 is an apocalyptic number.

3972121920 is a gapful number since it is divisible by the number (30) 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 3972121920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7398028638).

3972121920 is an abundant number, since it is smaller than the sum of its proper divisors (10823935356).

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

3972121920 is a wasteful number, since it uses less digits than its factorization.

3972121920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8210 (or 8184 counting only the distinct ones).

The product of its (nonzero) digits is 13608, while the sum is 36.

The square root of 3972121920 is about 63024.7722724962. The cubic root of 3972121920 is about 1583.7046434307.

The spelling of 3972121920 in words is "three billion, nine hundred seventy-two million, one hundred twenty-one thousand, nine hundred twenty".