21613040 has 20 divisors (see below), whose sum is σ = 50250504. Its totient is φ = 8645184.

The previous prime is 21613019. The next prime is 21613043. The reversal of 21613040 is 4031612.

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21613043) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135002 + ... + 135161.

Almost surely, 2^21613040 is an apocalyptic number.

21613040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21613040 is an abundant number, since it is smaller than the sum of its proper divisors (28637464).

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

21613040 is a wasteful number, since it uses less digits than its factorization.

21613040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270176 (or 270170 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21613040 is about 4648.9826844160. The cubic root of 21613040 is about 278.5513616302.

Adding to 21613040 its reverse (4031612), we get a palindrome (25644652).

The spelling of 21613040 in words is "twenty-one million, six hundred thirteen thousand, forty".