198405840 has 80 divisors (see below), whose sum is σ = 631709568. Its totient is φ = 51475968.

The previous prime is 198405821. The next prime is 198405887. The reversal of 198405840 is 48504891.

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

It is a super-2 number, since 2×198405840² = 78729754692211200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2292 + ... + 20051.

Almost surely, 2^198405840 is an apocalyptic number.

198405840 is a gapful number since it is divisible by the number (10) 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 198405840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (315854784).

198405840 is an abundant number, since it is smaller than the sum of its proper divisors (433303728).

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

198405840 is a wasteful number, since it uses less digits than its factorization.

198405840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22396 (or 22390 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 39.

The square root of 198405840 is about 14085.6607938712. The cubic root of 198405840 is about 583.2456169240.

The spelling of 198405840 in words is "one hundred ninety-eight million, four hundred five thousand, eight hundred forty".