21297671 has 4 divisors (see below), whose sum is σ = 21324744. Its totient is φ = 21270600.

The previous prime is 21297667. The next prime is 21297673. The reversal of 21297671 is 17679212.

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 21297671 - 2² = 21297667 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 (21297673) 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, 12320 + ... + 13941.

It is an arithmetic number, because the mean of its divisors is an integer number (5331186).

Almost surely, 2^21297671 is an apocalyptic number.

21297671 is a deficient number, since it is larger than the sum of its proper divisors (27073).

21297671 is an equidigital number, since it uses as much as digits as its factorization.

21297671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27072.

The product of its digits is 10584, while the sum is 35.

The square root of 21297671 is about 4614.9399779412. The cubic root of 21297671 is about 277.1898805396.

The spelling of 21297671 in words is "twenty-one million, two hundred ninety-seven thousand, six hundred seventy-one".