20491745 has 4 divisors (see below), whose sum is σ = 24590100. Its totient is φ = 16393392.

The previous prime is 20491739. The next prime is 20491753. The reversal of 20491745 is 54719402.

It is a happy number.

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 5180176 + 15311569 = 2276^2 + 3913^2 .

It is a cyclic number.

It is not a de Polignac number, because 20491745 - 2⁴ = 20491729 is a prime.

It is a super-2 number, since 2×20491745² = 839823226290050, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2049170 + ... + 2049179.

It is an arithmetic number, because the mean of its divisors is an integer number (6147525).

Almost surely, 2^20491745 is an apocalyptic number.

It is an amenable number.

20491745 is a deficient number, since it is larger than the sum of its proper divisors (4098355).

20491745 is an equidigital number, since it uses as much as digits as its factorization.

20491745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4098354.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 20491745 is about 4526.7808650298. The cubic root of 20491745 is about 273.6484426909.

The spelling of 20491745 in words is "twenty million, four hundred ninety-one thousand, seven hundred forty-five".