21534605 has 4 divisors (see below), whose sum is σ = 25841532. Its totient is φ = 17227680.

The previous prime is 21534577. The next prime is 21534659. The reversal of 21534605 is 50643512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16924996 + 4609609 = 4114^2 + 2147^2 .

It is not a de Polignac number, because 21534605 - 2⁸ = 21534349 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 3 ways as a sum of consecutive naturals, for example, 2153456 + ... + 2153465.

It is an arithmetic number, because the mean of its divisors is an integer number (6460383).

Almost surely, 2^21534605 is an apocalyptic number.

It is an amenable number.

21534605 is a deficient number, since it is larger than the sum of its proper divisors (4306927).

21534605 is an equidigital number, since it uses as much as digits as its factorization.

21534605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4306926.

The product of its (nonzero) digits is 3600, while the sum is 26.

The square root of 21534605 is about 4640.5393005555. The cubic root of 21534605 is about 278.2139934039.

The spelling of 21534605 in words is "twenty-one million, five hundred thirty-four thousand, six hundred five".