20641623621 has 4 divisors (see below), whose sum is σ = 27522164832. Its totient is φ = 13761082412.

The previous prime is 20641623599. The next prime is 20641623623. The reversal of 20641623621 is 12632614602.

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 20641623621 - 2⁵ = 20641623589 is a prime.

It is a super-2 number, since 2×20641623621² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20641623623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3440270601 + ... + 3440270606.

It is an arithmetic number, because the mean of its divisors is an integer number (6880541208).

Almost surely, 2^20641623621 is an apocalyptic number.

It is an amenable number.

20641623621 is a deficient number, since it is larger than the sum of its proper divisors (6880541211).

20641623621 is an equidigital number, since it uses as much as digits as its factorization.

20641623621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6880541210.

The product of its (nonzero) digits is 20736, while the sum is 33.

The spelling of 20641623621 in words is "twenty billion, six hundred forty-one million, six hundred twenty-three thousand, six hundred twenty-one".