21277609 has 2 divisors, whose sum is σ = 21277610. Its totient is φ = 21277608.

The previous prime is 21277603. The next prime is 21277621. The reversal of 21277609 is 90677212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21187609 + 90000 = 4603^2 + 300^2 .

It is a cyclic number.

It is not a de Polignac number, because 21277609 - 2⁵ = 21277577 is a prime.

It is not a weakly prime, because it can be changed into another prime (21277603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10638804 + 10638805.

It is an arithmetic number, because the mean of its divisors is an integer number (10638805).

Almost surely, 2^21277609 is an apocalyptic number.

It is an amenable number.

21277609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21277609 is an equidigital number, since it uses as much as digits as its factorization.

21277609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10584, while the sum is 34.

The square root of 21277609 is about 4612.7658730961. The cubic root of 21277609 is about 277.1028173358.

The spelling of 21277609 in words is "twenty-one million, two hundred seventy-seven thousand, six hundred nine".