19857408 has 68 divisors (see below), whose sum is σ = 53476968. Its totient is φ = 6553600.

The previous prime is 19857371. The next prime is 19857433. The reversal of 19857408 is 80475891.

It is a self number, because there is not a number n which added to its sum of digits gives 19857408.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 196558 + ... + 196658.

It is an arithmetic number, because the mean of its divisors is an integer number (786426).

Almost surely, 2^19857408 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19857408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26738484).

19857408 is an abundant number, since it is smaller than the sum of its proper divisors (33619560).

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

19857408 is an frugal number, since it uses more digits than its factorization.

19857408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136 (or 106 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 42.

The square root of 19857408 is about 4456.1651674955. The cubic root of 19857408 is about 270.7951320847.

The spelling of 19857408 in words is "nineteen million, eight hundred fifty-seven thousand, four hundred eight".