20311621 has 4 divisors (see below), whose sum is σ = 22158144. Its totient is φ = 18465100.

The previous prime is 20311619. The next prime is 20311657. The reversal of 20311621 is 12611302.

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 20311621 - 2¹ = 20311619 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20311595 and 20311604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20311601) 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, 923245 + ... + 923266.

It is an arithmetic number, because the mean of its divisors is an integer number (5539536).

Almost surely, 2^20311621 is an apocalyptic number.

It is an amenable number.

20311621 is a deficient number, since it is larger than the sum of its proper divisors (1846523).

20311621 is a wasteful number, since it uses less digits than its factorization.

20311621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1846522.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 20311621 is about 4506.8415769805. The cubic root of 20311621 is about 272.8442849779.

Adding to 20311621 its reverse (12611302), we get a palindrome (32922923).

The spelling of 20311621 in words is "twenty million, three hundred eleven thousand, six hundred twenty-one".