21672541 has 8 divisors (see below), whose sum is σ = 24458400. Its totient is φ = 19022640.

The previous prime is 21672527. The next prime is 21672571. The reversal of 21672541 is 14527612.

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

It is a cyclic number.

It is not a de Polignac number, because 21672541 - 2¹⁵ = 21639773 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21672571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33651 + ... + 34288.

It is an arithmetic number, because the mean of its divisors is an integer number (3057300).

Almost surely, 2^21672541 is an apocalyptic number.

It is an amenable number.

21672541 is a deficient number, since it is larger than the sum of its proper divisors (2785859).

21672541 is a wasteful number, since it uses less digits than its factorization.

21672541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67979.

The product of its digits is 3360, while the sum is 28.

The square root of 21672541 is about 4655.3776431134. The cubic root of 21672541 is about 278.8067460066.

Subtracting from 21672541 its reverse (14527612), we obtain a square (7144929 = 2673²).

The spelling of 21672541 in words is "twenty-one million, six hundred seventy-two thousand, five hundred forty-one".