20644641357 has 4 divisors (see below), whose sum is σ = 27526188480. Its totient is φ = 13763094236.

The previous prime is 20644641343. The next prime is 20644641359. The reversal of 20644641357 is 75314644602.

It is a happy number.

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 20644641357 - 2⁶ = 20644641293 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20644641359) 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, 3440773557 + ... + 3440773562.

It is an arithmetic number, because the mean of its divisors is an integer number (6881547120).

Almost surely, 2^20644641357 is an apocalyptic number.

It is an amenable number.

20644641357 is a deficient number, since it is larger than the sum of its proper divisors (6881547123).

20644641357 is an equidigital number, since it uses as much as digits as its factorization.

20644641357 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6881547122.

The product of its (nonzero) digits is 483840, while the sum is 42.

The spelling of 20644641357 in words is "twenty billion, six hundred forty-four million, six hundred forty-one thousand, three hundred fifty-seven".