21003996 has 36 divisors (see below), whose sum is σ = 53074392. Its totient is φ = 6462144.

The previous prime is 21003937. The next prime is 21004043. The reversal of 21003996 is 69930012.

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 11 ways as a sum of consecutive naturals, for example, 3151 + ... + 7206.

Almost surely, 2^21003996 is an apocalyptic number.

21003996 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21003996 is an abundant number, since it is smaller than the sum of its proper divisors (32070396).

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

21003996 is a wasteful number, since it uses less digits than its factorization.

21003996 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10390 (or 10375 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 30.

The square root of 21003996 is about 4583.0116735614. The cubic root of 21003996 is about 275.9099159902.

The spelling of 21003996 in words is "twenty-one million, three thousand, nine hundred ninety-six".