21401071 has 2 divisors, whose sum is σ = 21401072. Its totient is φ = 21401070.

The previous prime is 21401069. The next prime is 21401089. The reversal of 21401071 is 17010412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21401071 - 2¹ = 21401069 is a prime.

Together with 21401069, it forms a pair of twin primes.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21408071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10700535 + 10700536.

It is an arithmetic number, because the mean of its divisors is an integer number (10700536).

Almost surely, 2^21401071 is an apocalyptic number.

21401071 is a deficient number, since it is larger than the sum of its proper divisors (1).

21401071 is an equidigital number, since it uses as much as digits as its factorization.

21401071 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 56, while the sum is 16.

The square root of 21401071 is about 4626.1291594593. The cubic root of 21401071 is about 277.6377413203.

Adding to 21401071 its reverse (17010412), we get a palindrome (38411483).

The spelling of 21401071 in words is "twenty-one million, four hundred one thousand, seventy-one".