21930040 has 96 divisors (see below), whose sum is σ = 56881440. Its totient is φ = 7589120.

The previous prime is 21929993. The next prime is 21930101. The reversal of 21930040 is 4003912.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 111222 + ... + 111418.

It is an arithmetic number, because the mean of its divisors is an integer number (592515).

Almost surely, 2^21930040 is an apocalyptic number.

21930040 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 21930040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28440720).

21930040 is an abundant number, since it is smaller than the sum of its proper divisors (34951400).

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

21930040 is a wasteful number, since it uses less digits than its factorization.

21930040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 253 (or 238 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 19.

The square root of 21930040 is about 4682.9520603995. The cubic root of 21930040 is about 279.9066015020.

Adding to 21930040 its reverse (4003912), we get a palindrome (25933952).

The spelling of 21930040 in words is "twenty-one million, nine hundred thirty thousand, forty".