21745005 has 16 divisors (see below), whose sum is σ = 36305280. Its totient is φ = 11092928.

The previous prime is 21745001. The next prime is 21745007. The reversal of 21745005 is 50054712.

It is a cyclic number.

It is not a de Polignac number, because 21745005 - 2² = 21745001 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21745001) 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, 31170 + ... + 31859.

It is an arithmetic number, because the mean of its divisors is an integer number (2269080).

Almost surely, 2^21745005 is an apocalyptic number.

It is an amenable number.

21745005 is a deficient number, since it is larger than the sum of its proper divisors (14560275).

21745005 is a wasteful number, since it uses less digits than its factorization.

21745005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63060.

The product of its (nonzero) digits is 1400, while the sum is 24.

The square root of 21745005 is about 4663.1539755835. The cubic root of 21745005 is about 279.1171384128.

Adding to 21745005 its reverse (50054712), we get a palindrome (71799717).

The spelling of 21745005 in words is "twenty-one million, seven hundred forty-five thousand, five".