21271397 has 8 divisors (see below), whose sum is σ = 24643776. Its totient is φ = 17982432.

The previous prime is 21271381. The next prime is 21271409. The reversal of 21271397 is 79317212.

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 21271397 - 2⁴ = 21271381 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 (21270397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20303 + ... + 21324.

It is an arithmetic number, because the mean of its divisors is an integer number (3080472).

Almost surely, 2^21271397 is an apocalyptic number.

It is an amenable number.

21271397 is a deficient number, since it is larger than the sum of its proper divisors (3372379).

21271397 is an equidigital number, since it uses as much as digits as its factorization.

21271397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41707.

The product of its digits is 5292, while the sum is 32.

The square root of 21271397 is about 4612.0924752221. The cubic root of 21271397 is about 277.0758479796.

The spelling of 21271397 in words is "twenty-one million, two hundred seventy-one thousand, three hundred ninety-seven".