21030606 has 24 divisors (see below), whose sum is σ = 47965320. Its totient is φ = 6641136.

The previous prime is 21030589. The next prime is 21030613. The reversal of 21030606 is 60603012.

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 polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 30405 + ... + 31088.

It is an arithmetic number, because the mean of its divisors is an integer number (1998555).

Almost surely, 2^21030606 is an apocalyptic number.

21030606 is an abundant number, since it is smaller than the sum of its proper divisors (26934714).

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

21030606 is a wasteful number, since it uses less digits than its factorization.

21030606 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61520 (or 61517 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 21030606 is about 4585.9138674860. The cubic root of 21030606 is about 276.0263837412.

Adding to 21030606 its reverse (60603012), we get a palindrome (81633618).

The spelling of 21030606 in words is "twenty-one million, thirty thousand, six hundred six".