21455671 has 4 divisors (see below), whose sum is σ = 22035592. Its totient is φ = 20875752.

The previous prime is 21455663. The next prime is 21455677. The reversal of 21455671 is 17655412.

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 21455671 - 2³ = 21455663 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 (21455677) 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, 289905 + ... + 289978.

It is an arithmetic number, because the mean of its divisors is an integer number (5508898).

Almost surely, 2^21455671 is an apocalyptic number.

21455671 is a deficient number, since it is larger than the sum of its proper divisors (579921).

21455671 is an equidigital number, since it uses as much as digits as its factorization.

21455671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 579920.

The product of its digits is 8400, while the sum is 31.

The square root of 21455671 is about 4632.0266622721. The cubic root of 21455671 is about 277.8736508115.

The spelling of 21455671 in words is "twenty-one million, four hundred fifty-five thousand, six hundred seventy-one".