20989647 has 24 divisors (see below), whose sum is σ = 34835840. Its totient is φ = 11929680.

The previous prime is 20989627. The next prime is 20989651. The reversal of 20989647 is 74698902.

It is a happy number.

It is not a de Polignac number, because 20989647 - 2⁷ = 20989519 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20989607) 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 23 ways as a sum of consecutive naturals, for example, 12504 + ... + 14082.

Almost surely, 2^20989647 is an apocalyptic number.

20989647 is a deficient number, since it is larger than the sum of its proper divisors (13846193).

20989647 is a wasteful number, since it uses less digits than its factorization.

20989647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1803 (or 1800 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 45.

The square root of 20989647 is about 4581.4459507889. The cubic root of 20989647 is about 275.8470718648.

The spelling of 20989647 in words is "twenty million, nine hundred eighty-nine thousand, six hundred forty-seven".