20402439997 has 2 divisors, whose sum is σ = 20402439998. Its totient is φ = 20402439996.

The previous prime is 20402439991. The next prime is 20402440067. The reversal of 20402439997 is 79993420402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20393553636 + 8886361 = 142806^2 + 2981^2 .

It is a cyclic number.

It is not a de Polignac number, because 20402439997 - 2¹¹ = 20402437949 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20402439997.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20402439991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10201219998 + 10201219999.

It is an arithmetic number, because the mean of its divisors is an integer number (10201219999).

Almost surely, 2^20402439997 is an apocalyptic number.

It is an amenable number.

20402439997 is a deficient number, since it is larger than the sum of its proper divisors (1).

20402439997 is an equidigital number, since it uses as much as digits as its factorization.

20402439997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 979776, while the sum is 49.

The spelling of 20402439997 in words is "twenty billion, four hundred two million, four hundred thirty-nine thousand, nine hundred ninety-seven".