21439040 has 112 divisors (see below), whose sum is σ = 61886592. Its totient is φ = 6905856.

The previous prime is 21438961. The next prime is 21439079. The reversal of 21439040 is 4093412.

It is a tau number, because it is divible by the number of its divisors (112).

It is a super-2 number, since 2×21439040² = 919264872243200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21438997 and 21439015.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 37799 + ... + 38361.

Almost surely, 2^21439040 is an apocalyptic number.

21439040 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 21439040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30943296).

21439040 is an abundant number, since it is smaller than the sum of its proper divisors (40447552).

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

21439040 is a wasteful number, since it uses less digits than its factorization.

21439040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 604 (or 594 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21439040 is about 4630.2310957446. The cubic root of 21439040 is about 277.8018359015.

The spelling of 21439040 in words is "twenty-one million, four hundred thirty-nine thousand, forty".