21209896 has 8 divisors (see below), whose sum is σ = 39768570. Its totient is φ = 10604944.

The previous prime is 21209873. The next prime is 21209927. The reversal of 21209896 is 69890212.

It can be written as a sum of positive squares in only one way, i.e., 16924996 + 4284900 = 4114^2 + 2070^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1325611 + ... + 1325626.

Almost surely, 2^21209896 is an apocalyptic number.

It is an amenable number.

21209896 is a deficient number, since it is larger than the sum of its proper divisors (18558674).

21209896 is a wasteful number, since it uses less digits than its factorization.

21209896 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2651243 (or 2651239 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 21209896 is about 4605.4202848383. The cubic root of 21209896 is about 276.8085580456.

The spelling of 21209896 in words is "twenty-one million, two hundred nine thousand, eight hundred ninety-six".