21219621 has 8 divisors (see below), whose sum is σ = 29957184. Its totient is φ = 13314240.

The previous prime is 21219589. The next prime is 21219631. The reversal of 21219621 is 12691212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21219621 - 2⁵ = 21219589 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21219591 and 21219600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21219631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 207985 + ... + 208086.

It is an arithmetic number, because the mean of its divisors is an integer number (3744648).

Almost surely, 2^21219621 is an apocalyptic number.

It is an amenable number.

21219621 is a deficient number, since it is larger than the sum of its proper divisors (8737563).

21219621 is a wasteful number, since it uses less digits than its factorization.

21219621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 416091.

The product of its digits is 432, while the sum is 24.

The square root of 21219621 is about 4606.4759849586. The cubic root of 21219621 is about 276.8508582986.

The spelling of 21219621 in words is "twenty-one million, two hundred nineteen thousand, six hundred twenty-one".