21019912 has 16 divisors (see below), whose sum is σ = 39953340. Its totient is φ = 10365696.

The previous prime is 21019903. The next prime is 21019919. The reversal of 21019912 is 21991012.

It can be written as a sum of positive squares in 2 ways, for example, as 19660356 + 1359556 = 4434^2 + 1166^2 .

It is not an unprimeable number, because it can be changed into a prime (21019919) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17413 + ... + 18580.

Almost surely, 2^21019912 is an apocalyptic number.

It is an amenable number.

21019912 is a deficient number, since it is larger than the sum of its proper divisors (18933428).

21019912 is a wasteful number, since it uses less digits than its factorization.

21019912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36072 (or 36068 counting only the distinct ones).

The product of its (nonzero) digits is 324, while the sum is 25.

The square root of 21019912 is about 4584.7477575108. The cubic root of 21019912 is about 275.9795896130.

The spelling of 21019912 in words is "twenty-one million, nineteen thousand, nine hundred twelve".