3961394640 has 640 divisors, whose sum is σ = 16402283520. Its totient is φ = 859963392.

The previous prime is 3961394623. The next prime is 3961394687. The reversal of 3961394640 is 464931693.

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 127 ways as a sum of consecutive naturals, for example, 40839072 + ... + 40839168.

It is an arithmetic number, because the mean of its divisors is an integer number (25628568).

Almost surely, 2^3961394640 is an apocalyptic number.

3961394640 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 3961394640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8201141760).

3961394640 is an abundant number, since it is smaller than the sum of its proper divisors (12440888880).

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

3961394640 is a wasteful number, since it uses less digits than its factorization.

3961394640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236 (or 224 counting only the distinct ones).

The product of its (nonzero) digits is 419904, while the sum is 45.

The square root of 3961394640 is about 62939.6110569489. The cubic root of 3961394640 is about 1582.2776849038.

The spelling of 3961394640 in words is "three billion, nine hundred sixty-one million, three hundred ninety-four thousand, six hundred forty".