21457671 has 4 divisors (see below), whose sum is σ = 28610232. Its totient is φ = 14305112.

The previous prime is 21457649. The next prime is 21457679. The reversal of 21457671 is 17675412.

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 21457671 - 2⁹ = 21457159 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21457679) 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 3 ways as a sum of consecutive naturals, for example, 3576276 + ... + 3576281.

It is an arithmetic number, because the mean of its divisors is an integer number (7152558).

Almost surely, 2^21457671 is an apocalyptic number.

21457671 is a deficient number, since it is larger than the sum of its proper divisors (7152561).

21457671 is an equidigital number, since it uses as much as digits as its factorization.

21457671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7152560.

The product of its digits is 11760, while the sum is 33.

The square root of 21457671 is about 4632.2425454633. The cubic root of 21457671 is about 277.8822845822.

The spelling of 21457671 in words is "twenty-one million, four hundred fifty-seven thousand, six hundred seventy-one".