20421896 has 72 divisors (see below), whose sum is σ = 45322410. Its totient is φ = 8616960.

The previous prime is 20421883. The next prime is 20421899. The reversal of 20421896 is 69812402.

It can be written as a sum of positive squares in 3 ways, for example, as 20340100 + 81796 = 4510^2 + 286^2 .

It is not an unprimeable number, because it can be changed into a prime (20421899) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 279716 + ... + 279788.

Almost surely, 2^20421896 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 20421896, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22661205).

20421896 is an abundant number, since it is smaller than the sum of its proper divisors (24900514).

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

20421896 is a wasteful number, since it uses less digits than its factorization.

20421896 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135 (or 103 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 20421896 is about 4519.0591941244. The cubic root of 20421896 is about 273.3371656545.

The spelling of 20421896 in words is "twenty million, four hundred twenty-one thousand, eight hundred ninety-six".