21003788 has 24 divisors (see below), whose sum is σ = 40148640. Its totient is φ = 9555840.

The previous prime is 21003781. The next prime is 21003803. The reversal of 21003788 is 88730012.

It is a super-2 number, since 2×21003788² = 882318220697888, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21003788.

It is not an unprimeable number, because it can be changed into a prime (21003781) 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, 848 + ... + 6536.

It is an arithmetic number, because the mean of its divisors is an integer number (1672860).

Almost surely, 2^21003788 is an apocalyptic number.

It is an amenable number.

21003788 is a deficient number, since it is larger than the sum of its proper divisors (19144852).

21003788 is a wasteful number, since it uses less digits than its factorization.

21003788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5777 (or 5775 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 21003788 is about 4582.9889810036. The cubic root of 21003788 is about 275.9090052198.

The spelling of 21003788 in words is "twenty-one million, three thousand, seven hundred eighty-eight".