21497143 has 4 divisors (see below), whose sum is σ = 21710088. Its totient is φ = 21284200.

The previous prime is 21497141. The next prime is 21497183. The reversal of 21497143 is 34179412.

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

It is a cyclic number.

It is not a de Polignac number, because 21497143 - 2¹ = 21497141 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 (21497141) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106321 + ... + 106522.

It is an arithmetic number, because the mean of its divisors is an integer number (5427522).

Almost surely, 2^21497143 is an apocalyptic number.

21497143 is a deficient number, since it is larger than the sum of its proper divisors (212945).

21497143 is a wasteful number, since it uses less digits than its factorization.

21497143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212944.

The product of its digits is 6048, while the sum is 31.

The square root of 21497143 is about 4636.5011592795. The cubic root of 21497143 is about 278.0525710148.

The spelling of 21497143 in words is "twenty-one million, four hundred ninety-seven thousand, one hundred forty-three".