20689440 has 48 divisors (see below), whose sum is σ = 65173248. Its totient is φ = 5517056.

The previous prime is 20689439. The next prime is 20689453. The reversal of 20689440 is 4498602.

It is a tau number, because it is divible by the number of its divisors (48).

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 in 7 ways as a sum of consecutive naturals, for example, 21072 + ... + 22031.

It is an arithmetic number, because the mean of its divisors is an integer number (1357776).

Almost surely, 2^20689440 is an apocalyptic number.

20689440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20689440 is an abundant number, since it is smaller than the sum of its proper divisors (44483808).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20689440 is a wasteful number, since it uses less digits than its factorization.

20689440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43121 (or 43113 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 33.

The square root of 20689440 is about 4548.5646087530. The cubic root of 20689440 is about 274.5256395240.

The spelling of 20689440 in words is "twenty million, six hundred eighty-nine thousand, four hundred forty".