21497743 has 8 divisors (see below), whose sum is σ = 21843360. Its totient is φ = 21155040.

The previous prime is 21497731. The next prime is 21497761. The reversal of 21497743 is 34779412.

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-21497743 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 (21497783) 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 7 ways as a sum of consecutive naturals, for example, 17613 + ... + 18793.

It is an arithmetic number, because the mean of its divisors is an integer number (2730420).

Almost surely, 2^21497743 is an apocalyptic number.

21497743 is a deficient number, since it is larger than the sum of its proper divisors (345617).

21497743 is a wasteful number, since it uses less digits than its factorization.

21497743 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1457.

The product of its digits is 42336, while the sum is 37.

The square root of 21497743 is about 4636.5658627911. The cubic root of 21497743 is about 278.0551578700.

The spelling of 21497743 in words is "twenty-one million, four hundred ninety-seven thousand, seven hundred forty-three".