21277121 has 2 divisors, whose sum is σ = 21277122. Its totient is φ = 21277120.

The previous prime is 21277117. The next prime is 21277153. The reversal of 21277121 is 12177212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19492225 + 1784896 = 4415^2 + 1336^2 .

It is a cyclic number.

It is not a de Polignac number, because 21277121 - 2² = 21277117 is a prime.

It is not a weakly prime, because it can be changed into another prime (21277181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10638560 + 10638561.

It is an arithmetic number, because the mean of its divisors is an integer number (10638561).

Almost surely, 2^21277121 is an apocalyptic number.

It is an amenable number.

21277121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21277121 is an equidigital number, since it uses as much as digits as its factorization.

21277121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 392, while the sum is 23.

The square root of 21277121 is about 4612.7129761129. The cubic root of 21277121 is about 277.1006988771.

Subtracting from 21277121 its reverse (12177212), we obtain a palindrome (9099909).

The spelling of 21277121 in words is "twenty-one million, two hundred seventy-seven thousand, one hundred twenty-one".