21489705 has 48 divisors (see below), whose sum is σ = 40360320. Its totient is φ = 10948608.

The previous prime is 21489701. The next prime is 21489707. The reversal of 21489705 is 50798412.

It is not a de Polignac number, because 21489705 - 2² = 21489701 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21489705.

It is not an unprimeable number, because it can be changed into a prime (21489701) 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, 27561 + ... + 28329.

It is an arithmetic number, because the mean of its divisors is an integer number (840840).

Almost surely, 2^21489705 is an apocalyptic number.

It is an amenable number.

21489705 is a deficient number, since it is larger than the sum of its proper divisors (18870615).

21489705 is an equidigital number, since it uses as much as digits as its factorization.

21489705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 812 (or 800 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 21489705 is about 4635.6989764220. The cubic root of 21489705 is about 278.0204986351.

The spelling of 21489705 in words is "twenty-one million, four hundred eighty-nine thousand, seven hundred five".