21019520 has 32 divisors (see below), whose sum is σ = 50251320. Its totient is φ = 8407552.

The previous prime is 21019487. The next prime is 21019541. The reversal of 21019520 is 2591012.

It is a tau number, because it is divible by the number of its divisors (32).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21019492 and 21019501.

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, 15782 + ... + 17061.

Almost surely, 2^21019520 is an apocalyptic number.

21019520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21019520 is an abundant number, since it is smaller than the sum of its proper divisors (29231800).

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

21019520 is an equidigital number, since it uses as much as digits as its factorization.

21019520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32862 (or 32850 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 20.

The square root of 21019520 is about 4584.7050068679. The cubic root of 21019520 is about 275.9778740227.

The spelling of 21019520 in words is "twenty-one million, nineteen thousand, five hundred twenty".