21022621 has 4 divisors (see below), whose sum is σ = 21936672. Its totient is φ = 20108572.

The previous prime is 21022597. The next prime is 21022669. The reversal of 21022621 is 12622012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21022621 - 2¹³ = 21014429 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21022595 and 21022604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21022021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 456991 + ... + 457036.

It is an arithmetic number, because the mean of its divisors is an integer number (5484168).

Almost surely, 2^21022621 is an apocalyptic number.

It is an amenable number.

21022621 is a deficient number, since it is larger than the sum of its proper divisors (914051).

21022621 is an equidigital number, since it uses as much as digits as its factorization.

21022621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 914050.

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 21022621 is about 4585.0431840933. The cubic root of 21022621 is about 275.9914449844.

Adding to 21022621 its reverse (12622012), we get a palindrome (33644633).

The spelling of 21022621 in words is "twenty-one million, twenty-two thousand, six hundred twenty-one".