21789040 has 160 divisors (see below), whose sum is σ = 64745856. Its totient is φ = 6635520.

The previous prime is 21789037. The next prime is 21789043. The reversal of 21789040 is 4098712.

21789040 is nontrivially palindromic in base 3 and base 9.

It is an interprime number because it is at equal distance from previous prime (21789037) and next prime (21789043).

It is a zygodrome in base 3 and base 9.

It is a junction number, because it is equal to n+sod(n) for n = 21788993 and 21789011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21789043) 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, 298444 + ... + 298516.

Almost surely, 2^21789040 is an apocalyptic number.

21789040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21789040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32372928).

21789040 is an abundant number, since it is smaller than the sum of its proper divisors (42956816).

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

21789040 is a wasteful number, since it uses less digits than its factorization.

21789040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147 (or 141 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 21789040 is about 4667.8731773689. The cubic root of 21789040 is about 279.3054212833.

The spelling of 21789040 in words is "twenty-one million, seven hundred eighty-nine thousand, forty".