21381371 has 8 divisors (see below), whose sum is σ = 23457600. Its totient is φ = 19327240.

The previous prime is 21381361. The next prime is 21381379. The reversal of 21381371 is 17318312.

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 21381371 - 2⁶ = 21381307 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21381371.

It is not an unprimeable number, because it can be changed into a prime (21381379) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3461 + ... + 7398.

It is an arithmetic number, because the mean of its divisors is an integer number (2932200).

Almost surely, 2^21381371 is an apocalyptic number.

21381371 is a deficient number, since it is larger than the sum of its proper divisors (2076229).

21381371 is a wasteful number, since it uses less digits than its factorization.

21381371 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11049.

The product of its digits is 1008, while the sum is 26.

The square root of 21381371 is about 4623.9994593425. Note that the first 3 decimals coincide. The cubic root of 21381371 is about 277.5525252953.

Adding to 21381371 its reverse (17318312), we get a palindrome (38699683).

The spelling of 21381371 in words is "twenty-one million, three hundred eighty-one thousand, three hundred seventy-one".