20644491 has 32 divisors (see below), whose sum is σ = 32947200. Its totient is φ = 11249280.

The previous prime is 20644489. The next prime is 20644537. The reversal of 20644491 is 19444602.

It is not a de Polignac number, because 20644491 - 2¹ = 20644489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20644471) by changing a digit.

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 in 31 ways as a sum of consecutive naturals, for example, 66226 + ... + 66536.

It is an arithmetic number, because the mean of its divisors is an integer number (1029600).

Almost surely, 2^20644491 is an apocalyptic number.

20644491 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

20644491 is a deficient number, since it is larger than the sum of its proper divisors (12302709).

20644491 is a wasteful number, since it uses less digits than its factorization.

20644491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 459.

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 20644491 is about 4543.6209128843. The cubic root of 20644491 is about 274.3266877886.

It can be divided in two parts, 2064 and 4491, that added together give a triangular number (6555 = T₁₁₄).

The spelling of 20644491 in words is "twenty million, six hundred forty-four thousand, four hundred ninety-one".