3966721920 has 384 divisors, whose sum is σ = 15794887680. Its totient is φ = 898560000.

The previous prime is 3966721919. The next prime is 3966721931. The reversal of 3966721920 is 291276693.

It is a happy number.

3966721920 is a `hidden beast` number, since 396 + 6 + 72 + 192 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (45).

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, 5281545 + ... + 5282295.

It is an arithmetic number, because the mean of its divisors is an integer number (41132520).

Almost surely, 2^3966721920 is an apocalyptic number.

3966721920 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 3966721920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7897443840).

3966721920 is an abundant number, since it is smaller than the sum of its proper divisors (11828165760).

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

3966721920 is a wasteful number, since it uses less digits than its factorization.

3966721920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 914 (or 899 counting only the distinct ones).

The product of its (nonzero) digits is 244944, while the sum is 45.

The square root of 3966721920 is about 62981.9174049187. The cubic root of 3966721920 is about 1582.9866490699.

The spelling of 3966721920 in words is "three billion, nine hundred sixty-six million, seven hundred twenty-one thousand, nine hundred twenty".