21320046 has 96 divisors (see below), whose sum is σ = 53913600. Its totient is φ = 6027840.

The previous prime is 21320021. The next prime is 21320051. The reversal of 21320046 is 64002312.

It is a happy number.

It is a super-2 number, since 2×21320046² = 909088722884232, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 269835 + ... + 269913.

It is an arithmetic number, because the mean of its divisors is an integer number (561600).

Almost surely, 2^21320046 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21320046, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26956800).

21320046 is an abundant number, since it is smaller than the sum of its proper divisors (32593554).

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

21320046 is a wasteful number, since it uses less digits than its factorization.

21320046 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174 (or 171 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21320046 is about 4617.3635334463. The cubic root of 21320046 is about 277.2869170167.

Adding to 21320046 its reverse (64002312), we get a palindrome (85322358).

The spelling of 21320046 in words is "twenty-one million, three hundred twenty thousand, forty-six".