20919540 has 48 divisors (see below), whose sum is σ = 58988160. Its totient is φ = 5539200.

The previous prime is 20919533. The next prime is 20919557. The reversal of 20919540 is 4591902.

It is a happy number.

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 = 20919498 and 20919507.

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, 7906 + ... + 10214.

It is an arithmetic number, because the mean of its divisors is an integer number (1228920).

Almost surely, 2^20919540 is an apocalyptic number.

20919540 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 20919540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29494080).

20919540 is an abundant number, since it is smaller than the sum of its proper divisors (38068620).

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

20919540 is a wasteful number, since it uses less digits than its factorization.

20919540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2472 (or 2470 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 30.

The square root of 20919540 is about 4573.7883641463. The cubic root of 20919540 is about 275.5396126408.

The spelling of 20919540 in words is "twenty million, nine hundred nineteen thousand, five hundred forty".