20611621 has 4 divisors (see below), whose sum is σ = 21276544. Its totient is φ = 19946700.

The previous prime is 20611609. The next prime is 20611649. The reversal of 20611621 is 12611602.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12611602 = 2 ⋅6305801.

It is a cyclic number.

It is not a de Polignac number, because 20611621 - 2⁵ = 20611589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20611601) 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, 332415 + ... + 332476.

It is an arithmetic number, because the mean of its divisors is an integer number (5319136).

Almost surely, 2^20611621 is an apocalyptic number.

It is an amenable number.

20611621 is a deficient number, since it is larger than the sum of its proper divisors (664923).

20611621 is an equidigital number, since it uses as much as digits as its factorization.

20611621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 664922.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 20611621 is about 4540.0023127747. The cubic root of 20611621 is about 274.1810168341.

Subtracting from 20611621 its sum of digits (19), we obtain a palindrome (20611602).

The spelling of 20611621 in words is "twenty million, six hundred eleven thousand, six hundred twenty-one".