21121277 has 2 divisors, whose sum is σ = 21121278. Its totient is φ = 21121276.

The previous prime is 21121271. The next prime is 21121319. The reversal of 21121277 is 77212112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20016676 + 1104601 = 4474^2 + 1051^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21121277 is a prime.

It is a super-2 number, since 2×21121277² = 892216684221458, which contains 22 as substring.

It is a Chen prime.

It is equal to p_1337171 and since 21121277 and 1337171 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21121271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560638 + 10560639.

It is an arithmetic number, because the mean of its divisors is an integer number (10560639).

Almost surely, 2^21121277 is an apocalyptic number.

It is an amenable number.

21121277 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121277 is an equidigital number, since it uses as much as digits as its factorization.

21121277 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 21121277 is about 4595.7890508595. The cubic root of 21121277 is about 276.4225001806.

Adding to 21121277 its reverse (77212112), we get a palindrome (98333389).

The spelling of 21121277 in words is "twenty-one million, one hundred twenty-one thousand, two hundred seventy-seven".