19909539497 has 4 divisors (see below), whose sum is σ = 19910147076. Its totient is φ = 19908931920.

The previous prime is 19909539493. The next prime is 19909539527. The reversal of 19909539497 is 79493590991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 79493590991 = 487 ⋅163231193.

It can be written as a sum of positive squares in 2 ways, for example, as 6700404736 + 13209134761 = 81856^2 + 114931^2 .

It is a cyclic number.

It is not a de Polignac number, because 19909539497 - 2² = 19909539493 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19909539493) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 251654 + ... + 321167.

It is an arithmetic number, because the mean of its divisors is an integer number (4977536769).

Almost surely, 2^19909539497 is an apocalyptic number.

It is an amenable number.

19909539497 is a deficient number, since it is larger than the sum of its proper divisors (607579).

19909539497 is an equidigital number, since it uses as much as digits as its factorization.

19909539497 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 607578.

The product of its (nonzero) digits is 24800580, while the sum is 65.

The spelling of 19909539497 in words is "nineteen billion, nine hundred nine million, five hundred thirty-nine thousand, four hundred ninety-seven".