3921281408 has 128 divisors (see below), whose sum is σ = 9362131200. Its totient is φ = 1614919680.

The previous prime is 3921281407. The next prime is 3921281417. The reversal of 3921281408 is 8041821293.

It is a tau number, because it is divible by the number of its divisors (128).

It is a hoax number, since the sum of its digits (38) 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 (38).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3921281407) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 612110 + ... + 618482.

It is an arithmetic number, because the mean of its divisors is an integer number (73141650).

Almost surely, 2^3921281408 is an apocalyptic number.

3921281408 is a gapful number since it is divisible by the number (38) 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 3921281408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4681065600).

3921281408 is an abundant number, since it is smaller than the sum of its proper divisors (5440849792).

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

3921281408 is a wasteful number, since it uses less digits than its factorization.

3921281408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6440 (or 6428 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 38.

The square root of 3921281408 is about 62620.1358031105. The cubic root of 3921281408 is about 1576.9188214090.

The spelling of 3921281408 in words is "three billion, nine hundred twenty-one million, two hundred eighty-one thousand, four hundred eight".