21427771 has 2 divisors, whose sum is σ = 21427772. Its totient is φ = 21427770.

The previous prime is 21427751. The next prime is 21427787. The reversal of 21427771 is 17772412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21427771 - 2⁷ = 21427643 is a prime.

It is equal to p_1355287 and since 21427771 and 1355287 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21427711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10713885 + 10713886.

It is an arithmetic number, because the mean of its divisors is an integer number (10713886).

Almost surely, 2^21427771 is an apocalyptic number.

21427771 is a deficient number, since it is larger than the sum of its proper divisors (1).

21427771 is an equidigital number, since it uses as much as digits as its factorization.

21427771 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5488, while the sum is 31.

The square root of 21427771 is about 4629.0140418884. The cubic root of 21427771 is about 277.7531537224.

The spelling of 21427771 in words is "twenty-one million, four hundred twenty-seven thousand, seven hundred seventy-one".