20520817679 has 2 divisors, whose sum is σ = 20520817680. Its totient is φ = 20520817678.

The previous prime is 20520817663. The next prime is 20520817693. The reversal of 20520817679 is 97671802502.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20520817679 - 2⁴ = 20520817663 is a prime.

It is a super-2 number, since 2×20520817679² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20520817699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10260408839 + 10260408840.

It is an arithmetic number, because the mean of its divisors is an integer number (10260408840).

Almost surely, 2^20520817679 is an apocalyptic number.

20520817679 is a deficient number, since it is larger than the sum of its proper divisors (1).

20520817679 is an equidigital number, since it uses as much as digits as its factorization.

20520817679 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 423360, while the sum is 47.

The spelling of 20520817679 in words is "twenty billion, five hundred twenty million, eight hundred seventeen thousand, six hundred seventy-nine".