21110621 has 8 divisors (see below), whose sum is σ = 24619200. Its totient is φ = 18094524.

The previous prime is 21110611. The next prime is 21110647. The reversal of 21110621 is 12601112.

It is a de Polignac number, because none of the positive numbers 2^k-21110621 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21110596 and 21110605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21110611) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 30431 + ... + 31116.

It is an arithmetic number, because the mean of its divisors is an integer number (3077400).

Almost surely, 2^21110621 is an apocalyptic number.

It is an amenable number.

21110621 is a deficient number, since it is larger than the sum of its proper divisors (3508579).

21110621 is an frugal number, since it uses more digits than its factorization.

21110621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61568 (or 61554 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 14.

The square root of 21110621 is about 4594.6295824582. The cubic root of 21110621 is about 276.3760059328.

Adding to 21110621 its reverse (12601112), we get a palindrome (33711733).

The spelling of 21110621 in words is "twenty-one million, one hundred ten thousand, six hundred twenty-one".