21032406 has 32 divisors (see below), whose sum is σ = 47738880. Its totient is φ = 6860808.

The previous prime is 21032399. The next prime is 21032437. The reversal of 21032406 is 60423012.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1606 + ... + 6681.

It is an arithmetic number, because the mean of its divisors is an integer number (1491840).

Almost surely, 2^21032406 is an apocalyptic number.

21032406 is an abundant number, since it is smaller than the sum of its proper divisors (26706474).

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

21032406 is a wasteful number, since it uses less digits than its factorization.

21032406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8345 (or 8339 counting only the distinct ones).

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

The square root of 21032406 is about 4586.1101164276. The cubic root of 21032406 is about 276.0342585074.

Adding to 21032406 its reverse (60423012), we get a palindrome (81455418).

The spelling of 21032406 in words is "twenty-one million, thirty-two thousand, four hundred six".