21042497 has 8 divisors (see below), whose sum is σ = 24076800. Its totient is φ = 18015264.

The previous prime is 21042491. The next prime is 21042533. The reversal of 21042497 is 79424012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21042497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21042491) 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, 9029 + ... + 11117.

It is an arithmetic number, because the mean of its divisors is an integer number (3009600).

Almost surely, 2^21042497 is an apocalyptic number.

It is an amenable number.

21042497 is a deficient number, since it is larger than the sum of its proper divisors (3034303).

21042497 is a wasteful number, since it uses less digits than its factorization.

21042497 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3535.

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 21042497 is about 4587.2101543313. The cubic root of 21042497 is about 276.0783970041.

The spelling of 21042497 in words is "twenty-one million, forty-two thousand, four hundred ninety-seven".