21609996 has 12 divisors (see below), whose sum is σ = 50423352. Its totient is φ = 7203328.

The previous prime is 21609977. The next prime is 21610003. The reversal of 21609996 is 69990612.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 900405 + ... + 900428.

It is an arithmetic number, because the mean of its divisors is an integer number (4201946).

Almost surely, 2^21609996 is an apocalyptic number.

It is an amenable number.

21609996 is an abundant number, since it is smaller than the sum of its proper divisors (28813356).

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

21609996 is a wasteful number, since it uses less digits than its factorization.

21609996 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1800840 (or 1800838 counting only the distinct ones).

The product of its (nonzero) digits is 52488, while the sum is 42.

The square root of 21609996 is about 4648.6552894359. The cubic root of 21609996 is about 278.5382838747.

The spelling of 21609996 in words is "twenty-one million, six hundred nine thousand, nine hundred ninety-six".