19809397537 has 2 divisors, whose sum is σ = 19809397538. Its totient is φ = 19809397536.

The previous prime is 19809397463. The next prime is 19809397579. The reversal of 19809397537 is 73579390891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18474518241 + 1334879296 = 135921^2 + 36536^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19809397537 is a prime.

It is not a weakly prime, because it can be changed into another prime (19809397037) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9904698768 + 9904698769.

It is an arithmetic number, because the mean of its divisors is an integer number (9904698769).

Almost surely, 2^19809397537 is an apocalyptic number.

It is an amenable number.

19809397537 is a deficient number, since it is larger than the sum of its proper divisors (1).

19809397537 is an equidigital number, since it uses as much as digits as its factorization.

19809397537 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12859560, while the sum is 61.

The spelling of 19809397537 in words is "nineteen billion, eight hundred nine million, three hundred ninety-seven thousand, five hundred thirty-seven".