21272971 has 2 divisors, whose sum is σ = 21272972. Its totient is φ = 21272970.

The previous prime is 21272947. The next prime is 21272987. The reversal of 21272971 is 17927212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21272971 - 2⁷ = 21272843 is a prime.

It is a super-3 number, since 3×21272971³ (a number of 23 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21272371) by changing a digit.

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

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10636485 + 10636486.

It is an arithmetic number, because the mean of its divisors is an integer number (10636486).

Almost surely, 2^21272971 is an apocalyptic number.

21272971 is a deficient number, since it is larger than the sum of its proper divisors (1).

21272971 is an equidigital number, since it uses as much as digits as its factorization.

21272971 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3528, while the sum is 31.

The square root of 21272971 is about 4612.2631104481. The cubic root of 21272971 is about 277.0826819866.

The spelling of 21272971 in words is "twenty-one million, two hundred seventy-two thousand, nine hundred seventy-one".