21209496 has 128 divisors (see below), whose sum is σ = 69120000. Its totient is φ = 5258880.

The previous prime is 21209471. The next prime is 21209537. The reversal of 21209496 is 69490212.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 42255 + ... + 42753.

It is an arithmetic number, because the mean of its divisors is an integer number (540000).

Almost surely, 2^21209496 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21209496, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34560000).

21209496 is an abundant number, since it is smaller than the sum of its proper divisors (47910504).

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

21209496 is a wasteful number, since it uses less digits than its factorization.

21209496 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 549 (or 545 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 33.

The square root of 21209496 is about 4605.3768575438. The cubic root of 21209496 is about 276.8068179126.

The spelling of 21209496 in words is "twenty-one million, two hundred nine thousand, four hundred ninety-six".