19927661009 has 4 divisors (see below), whose sum is σ = 20005200804. Its totient is φ = 19850121216.

The previous prime is 19927661003. The next prime is 19927661023. The reversal of 19927661009 is 90016672991.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15204123025 + 4723537984 = 123305^2 + 68728^2 .

It is a cyclic number.

It is not a de Polignac number, because 19927661009 - 2¹² = 19927656913 is a prime.

It is a super-2 number, since 2×19927661009² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19927661003) 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, 38769512 + ... + 38770025.

It is an arithmetic number, because the mean of its divisors is an integer number (5001300201).

Almost surely, 2^19927661009 is an apocalyptic number.

It is an amenable number.

19927661009 is a deficient number, since it is larger than the sum of its proper divisors (77539795).

19927661009 is an equidigital number, since it uses as much as digits as its factorization.

19927661009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77539794.

The product of its (nonzero) digits is 367416, while the sum is 50.

The spelling of 19927661009 in words is "nineteen billion, nine hundred twenty-seven million, six hundred sixty-one thousand, nine".