21008912 has 10 divisors (see below), whose sum is σ = 40704798. Its totient is φ = 10504448.

The previous prime is 21008903. The next prime is 21008941. The reversal of 21008912 is 21980012.

It can be written as a sum of positive squares in only one way, i.e., 20394256 + 614656 = 4516^2 + 784^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 656513 + ... + 656544.

Almost surely, 2^21008912 is an apocalyptic number.

It is an amenable number.

21008912 is a deficient number, since it is larger than the sum of its proper divisors (19695886).

21008912 is a wasteful number, since it uses less digits than its factorization.

21008912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1313065 (or 1313059 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 21008912 is about 4583.5479707318. The cubic root of 21008912 is about 275.9314399475.

Adding to 21008912 its reverse (21980012), we get a palindrome (42988924).

The spelling of 21008912 in words is "twenty-one million, eight thousand, nine hundred twelve".