20127591787 has 4 divisors (see below), whose sum is σ = 20326874976. Its totient is φ = 19928308600.

The previous prime is 20127591769. The next prime is 20127591791. The reversal of 20127591787 is 78719572102.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78719572102 = 2 ⋅39359786051.

It is a cyclic number.

It is not a de Polignac number, because 20127591787 - 2¹⁵ = 20127559019 is a prime.

It is a super-2 number, since 2×20127591787² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20127591787.

It is not an unprimeable number, because it can be changed into a prime (20127591287) 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, 99641443 + ... + 99641644.

It is an arithmetic number, because the mean of its divisors is an integer number (5081718744).

Almost surely, 2^20127591787 is an apocalyptic number.

20127591787 is a deficient number, since it is larger than the sum of its proper divisors (199283189).

20127591787 is a wasteful number, since it uses less digits than its factorization.

20127591787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199283188.

The product of its (nonzero) digits is 493920, while the sum is 49.

The spelling of 20127591787 in words is "twenty billion, one hundred twenty-seven million, five hundred ninety-one thousand, seven hundred eighty-seven".