19517940 has 144 divisors (see below), whose sum is σ = 67267200. Its totient is φ = 4541184.

The previous prime is 19517923. The next prime is 19517969. The reversal of 19517940 is 4971591.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 19517895 and 19517904.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 44241 + ... + 44679.

Almost surely, 2^19517940 is an apocalyptic number.

19517940 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 19517940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33633600).

19517940 is an abundant number, since it is smaller than the sum of its proper divisors (47749260).

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

19517940 is a wasteful number, since it uses less digits than its factorization.

19517940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 486 (or 481 counting only the distinct ones).

The product of its (nonzero) digits is 11340, while the sum is 36.

The square root of 19517940 is about 4417.9112711778. The cubic root of 19517940 is about 269.2431478976.

The spelling of 19517940 in words is "nineteen million, five hundred seventeen thousand, nine hundred forty".