21152497 has 4 divisors (see below), whose sum is σ = 21165300. Its totient is φ = 21139696.

The previous prime is 21152477. The next prime is 21152507. The reversal of 21152497 is 79425112.

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 14371681 + 6780816 = 3791^2 + 2604^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21152497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21152477) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3478 + ... + 7375.

It is an arithmetic number, because the mean of its divisors is an integer number (5291325).

Almost surely, 2^21152497 is an apocalyptic number.

It is an amenable number.

21152497 is a deficient number, since it is larger than the sum of its proper divisors (12803).

21152497 is a wasteful number, since it uses less digits than its factorization.

21152497 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12802.

The product of its digits is 5040, while the sum is 31.

The square root of 21152497 is about 4599.1843842142. The cubic root of 21152497 is about 276.5586292903.

The spelling of 21152497 in words is "twenty-one million, one hundred fifty-two thousand, four hundred ninety-seven".