20623621 has 2 divisors, whose sum is σ = 20623622. Its totient is φ = 20623620.

The previous prime is 20623619. The next prime is 20623643. The reversal of 20623621 is 12632602.

It is a happy number.

It is an a-pointer prime, because the next prime (20623643) can be obtained adding 20623621 to its sum of digits (22).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10982596 + 9641025 = 3314^2 + 3105^2 .

It is a cyclic number.

It is not a de Polignac number, because 20623621 - 2¹ = 20623619 is a prime.

Together with 20623619, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 20623592 and 20623601.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20623121) 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 as a sum of consecutive naturals, namely, 10311810 + 10311811.

It is an arithmetic number, because the mean of its divisors is an integer number (10311811).

Almost surely, 2^20623621 is an apocalyptic number.

It is an amenable number.

20623621 is a deficient number, since it is larger than the sum of its proper divisors (1).

20623621 is an equidigital number, since it uses as much as digits as its factorization.

20623621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 20623621 is about 4541.3237057052. The cubic root of 20623621 is about 274.2342155272.

The spelling of 20623621 in words is "twenty million, six hundred twenty-three thousand, six hundred twenty-one".