20506239997 has 2 divisors, whose sum is σ = 20506239998. Its totient is φ = 20506239996.

The previous prime is 20506239989. The next prime is 20506240043. The reversal of 20506239997 is 79993260502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14678291716 + 5827948281 = 121154^2 + 76341^2 .

It is a cyclic number.

It is not a de Polignac number, because 20506239997 - 2³ = 20506239989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20506239947) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10253119998 + 10253119999.

It is an arithmetic number, because the mean of its divisors is an integer number (10253119999).

Almost surely, 2^20506239997 is an apocalyptic number.

It is an amenable number.

20506239997 is a deficient number, since it is larger than the sum of its proper divisors (1).

20506239997 is an equidigital number, since it uses as much as digits as its factorization.

20506239997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1837080, while the sum is 52.

The spelling of 20506239997 in words is "twenty billion, five hundred six million, two hundred thirty-nine thousand, nine hundred ninety-seven".