21907080 has 192 divisors, whose sum is σ = 79672320. Its totient is φ = 5184000.

The previous prime is 21907027. The next prime is 21907087. The reversal of 21907080 is 8070912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21907087) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 145005 + ... + 145155.

It is an arithmetic number, because the mean of its divisors is an integer number (414960).

Almost surely, 2^21907080 is an apocalyptic number.

21907080 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is a pronic number, being equal to 4680×4681.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21907080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39836160).

21907080 is an abundant number, since it is smaller than the sum of its proper divisors (57765240).

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

21907080 is a wasteful number, since it uses less digits than its factorization.

21907080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212 (or 205 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 21907080 is about 4680.4999732935. The cubic root of 21907080 is about 279.8088831864.

Adding to 21907080 its reverse (8070912), we get a palindrome (29977992).

The spelling of 21907080 in words is "twenty-one million, nine hundred seven thousand, eighty".