21745460 has 48 divisors (see below), whose sum is σ = 50379840. Its totient is φ = 7818240.

The previous prime is 21745441. The next prime is 21745469. The reversal of 21745460 is 6454712.

It is a super-2 number, since 2×21745460² = 945730061223200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21745469) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20831 + ... + 21849.

It is an arithmetic number, because the mean of its divisors is an integer number (1049580).

Almost surely, 2^21745460 is an apocalyptic number.

21745460 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 21745460, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25189920).

21745460 is an abundant number, since it is smaller than the sum of its proper divisors (28634380).

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

21745460 is a wasteful number, since it uses less digits than its factorization.

21745460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1136 (or 1134 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 29.

The square root of 21745460 is about 4663.2027620510. The cubic root of 21745460 is about 279.1190851804.

The spelling of 21745460 in words is "twenty-one million, seven hundred forty-five thousand, four hundred sixty".