21497605 has 8 divisors (see below), whose sum is σ = 27314712. Its totient is φ = 16186368.

The previous prime is 21497603. The next prime is 21497621. The reversal of 21497605 is 50679412.

It can be written as a sum of positive squares in 4 ways, for example, as 1766241 + 19731364 = 1329^2 + 4442^2 .

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 21497605 - 2¹ = 21497603 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21497603) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 126372 + ... + 126541.

It is an arithmetic number, because the mean of its divisors is an integer number (3414339).

Almost surely, 2^21497605 is an apocalyptic number.

It is an amenable number.

21497605 is a deficient number, since it is larger than the sum of its proper divisors (5817107).

21497605 is a wasteful number, since it uses less digits than its factorization.

21497605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252935.

The product of its (nonzero) digits is 15120, while the sum is 34.

The square root of 21497605 is about 4636.5509810634. The cubic root of 21497605 is about 278.0545628976.

The spelling of 21497605 in words is "twenty-one million, four hundred ninety-seven thousand, six hundred five".