21480640 has 56 divisors (see below), whose sum is σ = 53858160. Its totient is φ = 8137728.

The previous prime is 21480637. The next prime is 21480647. The reversal of 21480640 is 4608412.

It is a super-2 number, since 2×21480640² = 922835789619200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21480647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4314 + ... + 7846.

Almost surely, 2^21480640 is an apocalyptic number.

21480640 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 21480640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26929080).

21480640 is an abundant number, since it is smaller than the sum of its proper divisors (32377520).

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

21480640 is a wasteful number, since it uses less digits than its factorization.

21480640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3569 (or 3559 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 25.

The square root of 21480640 is about 4634.7211350846. The cubic root of 21480640 is about 277.9814006845.

The spelling of 21480640 in words is "twenty-one million, four hundred eighty thousand, six hundred forty".