21438371 has 4 divisors (see below), whose sum is σ = 21488544. Its totient is φ = 21388200.

The previous prime is 21438359. The next prime is 21438401. The reversal of 21438371 is 17383412.

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 21438371 - 2¹⁰ = 21437347 is a prime.

It is a super-2 number, since 2×21438371² = 919207502267282, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21438301) 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, 24440 + ... + 25301.

It is an arithmetic number, because the mean of its divisors is an integer number (5372136).

Almost surely, 2^21438371 is an apocalyptic number.

21438371 is a deficient number, since it is larger than the sum of its proper divisors (50173).

21438371 is an equidigital number, since it uses as much as digits as its factorization.

21438371 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50172.

The product of its digits is 4032, while the sum is 29.

The square root of 21438371 is about 4630.1588525665. The cubic root of 21438371 is about 277.7989462920.

The spelling of 21438371 in words is "twenty-one million, four hundred thirty-eight thousand, three hundred seventy-one".