21171443 has 4 divisors (see below), whose sum is σ = 22416840. Its totient is φ = 19926048.

The previous prime is 21171407. The next prime is 21171461. The reversal of 21171443 is 34417112.

It is a happy number.

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 21171443 - 2⁶ = 21171379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21171463) 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, 622673 + ... + 622706.

It is an arithmetic number, because the mean of its divisors is an integer number (5604210).

Almost surely, 2^21171443 is an apocalyptic number.

21171443 is a deficient number, since it is larger than the sum of its proper divisors (1245397).

21171443 is a wasteful number, since it uses less digits than its factorization.

21171443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1245396.

The product of its digits is 672, while the sum is 23.

The square root of 21171443 is about 4601.2436362358. The cubic root of 21171443 is about 276.6411745677.

Adding to 21171443 its reverse (34417112), we get a palindrome (55588555).

The spelling of 21171443 in words is "twenty-one million, one hundred seventy-one thousand, four hundred forty-three".