21477689 has 2 divisors, whose sum is σ = 21477690. Its totient is φ = 21477688.

The previous prime is 21477623. The next prime is 21477697. The reversal of 21477689 is 98677412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20322064 + 1155625 = 4508^2 + 1075^2 .

It is a cyclic number.

It is not a de Polignac number, because 21477689 - 2¹² = 21473593 is a prime.

It is a super-2 number, since 2×21477689² = 922582249561442, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21477089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10738844 + 10738845.

It is an arithmetic number, because the mean of its divisors is an integer number (10738845).

Almost surely, 2^21477689 is an apocalyptic number.

It is an amenable number.

21477689 is a deficient number, since it is larger than the sum of its proper divisors (1).

21477689 is an equidigital number, since it uses as much as digits as its factorization.

21477689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 169344, while the sum is 44.

The square root of 21477689 is about 4634.4027662688. The cubic root of 21477689 is about 277.9686704511.

The spelling of 21477689 in words is "twenty-one million, four hundred seventy-seven thousand, six hundred eighty-nine".