21485405 has 8 divisors (see below), whose sum is σ = 26269272. Its totient is φ = 16863808.

The previous prime is 21485357. The next prime is 21485413. The reversal of 21485405 is 50458412.

It can be written as a sum of positive squares in 4 ways, for example, as 8213956 + 13271449 = 2866^2 + 3643^2 .

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 21485405 - 2⁶ = 21485341 is a prime.

It is a Duffinian number.

It is a congruent number.

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, 40274 + ... + 40803.

It is an arithmetic number, because the mean of its divisors is an integer number (3283659).

Almost surely, 2^21485405 is an apocalyptic number.

It is an amenable number.

21485405 is a deficient number, since it is larger than the sum of its proper divisors (4783867).

21485405 is an equidigital number, since it uses as much as digits as its factorization.

21485405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81135.

The product of its (nonzero) digits is 6400, while the sum is 29.

The square root of 21485405 is about 4635.2351612405. The cubic root of 21485405 is about 278.0019538189.

The spelling of 21485405 in words is "twenty-one million, four hundred eighty-five thousand, four hundred five".