20646426397 has 2 divisors, whose sum is σ = 20646426398. Its totient is φ = 20646426396.

The previous prime is 20646426389. The next prime is 20646426413. The reversal of 20646426397 is 79362464602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15858616761 + 4787809636 = 125931^2 + 69194^2 .

It is a cyclic number.

It is not a de Polignac number, because 20646426397 - 2³ = 20646426389 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20646426397.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20646426337) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10323213198 + 10323213199.

It is an arithmetic number, because the mean of its divisors is an integer number (10323213199).

Almost surely, 2^20646426397 is an apocalyptic number.

It is an amenable number.

20646426397 is a deficient number, since it is larger than the sum of its proper divisors (1).

20646426397 is an equidigital number, since it uses as much as digits as its factorization.

20646426397 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2612736, while the sum is 49.

The spelling of 20646426397 in words is "twenty billion, six hundred forty-six million, four hundred twenty-six thousand, three hundred ninety-seven".