20198640 has 160 divisors (see below), whose sum is σ = 78137856. Its totient is φ = 4193280.

The previous prime is 20198627. The next prime is 20198657. The reversal of 20198640 is 4689102.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 20198598 and 20198607.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 17934 + ... + 19026.

Almost surely, 2^20198640 is an apocalyptic number.

20198640 is a gapful number since it is divisible by the number (20) 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 20198640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39068928).

20198640 is an abundant number, since it is smaller than the sum of its proper divisors (57939216).

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

20198640 is a wasteful number, since it uses less digits than its factorization.

20198640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1127 (or 1121 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 20198640 is about 4494.2897102879. The cubic root of 20198640 is about 272.3374560188.

The spelling of 20198640 in words is "twenty million, one hundred ninety-eight thousand, six hundred forty".