21745505 has 8 divisors (see below), whose sum is σ = 26994600. Its totient is φ = 16796416.

The previous prime is 21745483. The next prime is 21745517. The reversal of 21745505 is 50554712.

It can be written as a sum of positive squares in 4 ways, for example, as 1936 + 21743569 = 44^2 + 4663^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21745505 - 2⁶ = 21745441 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 74840 + ... + 75129.

It is an arithmetic number, because the mean of its divisors is an integer number (3374325).

Almost surely, 2^21745505 is an apocalyptic number.

It is an amenable number.

21745505 is a deficient number, since it is larger than the sum of its proper divisors (5249095).

21745505 is a wasteful number, since it uses less digits than its factorization.

21745505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150003.

The product of its (nonzero) digits is 7000, while the sum is 29.

The square root of 21745505 is about 4663.2075870585. The cubic root of 21745505 is about 279.1192777164.

The spelling of 21745505 in words is "twenty-one million, seven hundred forty-five thousand, five hundred five".