20391188 has 6 divisors (see below), whose sum is σ = 35684586. Its totient is φ = 10195592.

The previous prime is 20391169. The next prime is 20391197. The reversal of 20391188 is 88119302.

It can be written as a sum of positive squares in only one way, i.e., 19465744 + 925444 = 4412^2 + 962^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2548895 + ... + 2548902.

It is an arithmetic number, because the mean of its divisors is an integer number (5947431).

Almost surely, 2^20391188 is an apocalyptic number.

It is an amenable number.

20391188 is a deficient number, since it is larger than the sum of its proper divisors (15293398).

20391188 is a wasteful number, since it uses less digits than its factorization.

20391188 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5097801 (or 5097799 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 32.

The square root of 20391188 is about 4515.6603060904. The cubic root of 20391188 is about 273.2000930354.

The spelling of 20391188 in words is "twenty million, three hundred ninety-one thousand, one hundred eighty-eight".