21678489 has 32 divisors (see below), whose sum is σ = 38307840. Its totient is φ = 11846736.

The previous prime is 21678479. The next prime is 21678491. The reversal of 21678489 is 98487612.

21678489 is a `hidden beast` number, since 2 + 167 + 8 + 489 = 666.

It is not a de Polignac number, because 21678489 - 2⁷ = 21678361 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21678439) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1854 + ... + 6840.

It is an arithmetic number, because the mean of its divisors is an integer number (1197120).

Almost surely, 2^21678489 is an apocalyptic number.

It is an amenable number.

21678489 is a deficient number, since it is larger than the sum of its proper divisors (16629351).

21678489 is a wasteful number, since it uses less digits than its factorization.

21678489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5026 (or 5020 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 21678489 is about 4656.0164303834. The cubic root of 21678489 is about 278.8322497202.

The spelling of 21678489 in words is "twenty-one million, six hundred seventy-eight thousand, four hundred eighty-nine".