21213696 has 80 divisors (see below), whose sum is σ = 64620864. Its totient is φ = 6057984.

The previous prime is 21213679. The next prime is 21213697. The reversal of 21213696 is 69631212.

It is not an unprimeable number, because it can be changed into a prime (21213697) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9766 + ... + 11738.

Almost surely, 2^21213696 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 21213696, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32310432).

21213696 is an abundant number, since it is smaller than the sum of its proper divisors (43407168).

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

21213696 is an equidigital number, since it uses as much as digits as its factorization.

21213696 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2001 (or 1985 counting only the distinct ones).

The product of its digits is 3888, while the sum is 30.

The square root of 21213696 is about 4605.8328237139. The cubic root of 21213696 is about 276.8250882180.

The spelling of 21213696 in words is "twenty-one million, two hundred thirteen thousand, six hundred ninety-six".