21271501 has 2 divisors, whose sum is σ = 21271502. Its totient is φ = 21271500.

The previous prime is 21271499. The next prime is 21271519. The reversal of 21271501 is 10517212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21068100 + 203401 = 4590^2 + 451^2 .

It is a cyclic number.

It is not a de Polignac number, because 21271501 - 2¹ = 21271499 is a prime.

Together with 21271499, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21278501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10635750 + 10635751.

It is an arithmetic number, because the mean of its divisors is an integer number (10635751).

Almost surely, 2^21271501 is an apocalyptic number.

It is an amenable number.

21271501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21271501 is an equidigital number, since it uses as much as digits as its factorization.

21271501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 21271501 is about 4612.1037499172. The cubic root of 21271501 is about 277.0762995382.

Adding to 21271501 its reverse (10517212), we get a palindrome (31788713).

The spelling of 21271501 in words is "twenty-one million, two hundred seventy-one thousand, five hundred one".