39897840 has 80 divisors (see below), whose sum is σ = 127054368. Its totient is φ = 10349568.

The previous prime is 39897829. The next prime is 39897841. The reversal of 39897840 is 4879893.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 39897840.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39897841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6634 + ... + 11126.

Almost surely, 2^39897840 is an apocalyptic number.

39897840 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 39897840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (63527184).

39897840 is an abundant number, since it is smaller than the sum of its proper divisors (87156528).

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

39897840 is a wasteful number, since it uses less digits than its factorization.

39897840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4546 (or 4540 counting only the distinct ones).

The product of its (nonzero) digits is 435456, while the sum is 48.

The square root of 39897840 is about 6316.4736997790. The cubic root of 39897840 is about 341.7037892112.

The spelling of 39897840 in words is "thirty-nine million, eight hundred ninety-seven thousand, eight hundred forty".