20557006643 has 2 divisors, whose sum is σ = 20557006644. Its totient is φ = 20557006642.

The previous prime is 20557006621. The next prime is 20557006711. The reversal of 20557006643 is 34660075502.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20557006643 - 2⁶ = 20557006579 is a prime.

It is a super-2 number, since 2×20557006643² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 20557006597 and 20557006606.

It is not a weakly prime, because it can be changed into another prime (20557002643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10278503321 + 10278503322.

It is an arithmetic number, because the mean of its divisors is an integer number (10278503322).

Almost surely, 2^20557006643 is an apocalyptic number.

20557006643 is a deficient number, since it is larger than the sum of its proper divisors (1).

20557006643 is an equidigital number, since it uses as much as digits as its factorization.

20557006643 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 151200, while the sum is 38.

The spelling of 20557006643 in words is "twenty billion, five hundred fifty-seven million, six thousand, six hundred forty-three".