19561139405 has 8 divisors (see below), whose sum is σ = 23474181984. Its totient is φ = 15648368400.

The previous prime is 19561139399. The next prime is 19561139413. The reversal of 19561139405 is 50493116591.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 19561139405 - 2¹⁶ = 19561073869 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 160310 + ... + 254600.

It is an arithmetic number, because the mean of its divisors is an integer number (2934272748).

Almost surely, 2^19561139405 is an apocalyptic number.

It is an amenable number.

19561139405 is a deficient number, since it is larger than the sum of its proper divisors (3913042579).

19561139405 is an equidigital number, since it uses as much as digits as its factorization.

19561139405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135787.

The product of its (nonzero) digits is 145800, while the sum is 44.

The spelling of 19561139405 in words is "nineteen billion, five hundred sixty-one million, one hundred thirty-nine thousand, four hundred five".