21145660 has 24 divisors (see below), whose sum is σ = 44500176. Its totient is φ = 8440320.

The previous prime is 21145639. The next prime is 21145667. The reversal of 21145660 is 6654112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21145667) 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, 12675 + ... + 14245.

It is an arithmetic number, because the mean of its divisors is an integer number (1854174).

Almost surely, 2^21145660 is an apocalyptic number.

21145660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21145660 is an abundant number, since it is smaller than the sum of its proper divisors (23354516).

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

21145660 is a wasteful number, since it uses less digits than its factorization.

21145660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2253 (or 2251 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21145660 is about 4598.4410401787. The cubic root of 21145660 is about 276.5288292608.

Adding to 21145660 its reverse (6654112), we get a palindrome (27799772).

The spelling of 21145660 in words is "twenty-one million, one hundred forty-five thousand, six hundred sixty".