21019728 has 40 divisors (see below), whose sum is σ = 54684000. Its totient is φ = 6957184.

The previous prime is 21019727. The next prime is 21019729. The reversal of 21019728 is 82791012.

It is an interprime number because it is at equal distance from previous prime (21019727) and next prime (21019729).

It is a junction number, because it is equal to n+sod(n) for n = 21019695 and 21019704.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21019727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5683 + ... + 8621.

It is an arithmetic number, because the mean of its divisors is an integer number (1367100).

Almost surely, 2^21019728 is an apocalyptic number.

It is an amenable number.

21019728 is an abundant number, since it is smaller than the sum of its proper divisors (33664272).

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

21019728 is a wasteful number, since it uses less digits than its factorization.

21019728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3099 (or 3093 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 30.

The square root of 21019728 is about 4584.7276909321. The cubic root of 21019728 is about 275.9787843386.

The spelling of 21019728 in words is "twenty-one million, nineteen thousand, seven hundred twenty-eight".