20172188537 has 4 divisors (see below), whose sum is σ = 20198836836. Its totient is φ = 20145540240.

The previous prime is 20172188521. The next prime is 20172188557. The reversal of 20172188537 is 73588127102.

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 12197877136 + 7974311401 = 110444^2 + 89299^2 .

It is a cyclic number.

It is not a de Polignac number, because 20172188537 - 2⁴ = 20172188521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20172188557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13323014 + ... + 13324527.

It is an arithmetic number, because the mean of its divisors is an integer number (5049709209).

Almost surely, 2^20172188537 is an apocalyptic number.

It is an amenable number.

20172188537 is a deficient number, since it is larger than the sum of its proper divisors (26648299).

20172188537 is an equidigital number, since it uses as much as digits as its factorization.

20172188537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26648298.

The product of its (nonzero) digits is 188160, while the sum is 44.

The spelling of 20172188537 in words is "twenty billion, one hundred seventy-two million, one hundred eighty-eight thousand, five hundred thirty-seven".