21320436 has 48 divisors (see below), whose sum is σ = 52774400. Its totient is φ = 6687360.

The previous prime is 21320407. The next prime is 21320447. The reversal of 21320436 is 63402312.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12990 + ... + 14538.

Almost surely, 2^21320436 is an apocalyptic number.

It is an amenable number.

21320436 is an abundant number, since it is smaller than the sum of its proper divisors (31453964).

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

21320436 is a wasteful number, since it uses less digits than its factorization.

21320436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1624 (or 1622 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 21.

The square root of 21320436 is about 4617.4057651456. The cubic root of 21320436 is about 277.2886077766.

Adding to 21320436 its reverse (63402312), we get a palindrome (84722748).

The spelling of 21320436 in words is "twenty-one million, three hundred twenty thousand, four hundred thirty-six".