21346681 has 2 divisors, whose sum is σ = 21346682. Its totient is φ = 21346680.

The previous prime is 21346673. The next prime is 21346711. The reversal of 21346681 is 18664312.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16974400 + 4372281 = 4120^2 + 2091^2 .

It is a cyclic number.

It is not a de Polignac number, because 21346681 - 2³ = 21346673 is a prime.

It is a super-2 number, since 2×21346681² = 911361579431522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21346621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10673340 + 10673341.

It is an arithmetic number, because the mean of its divisors is an integer number (10673341).

Almost surely, 2^21346681 is an apocalyptic number.

It is an amenable number.

21346681 is a deficient number, since it is larger than the sum of its proper divisors (1).

21346681 is an equidigital number, since it uses as much as digits as its factorization.

21346681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6912, while the sum is 31.

The square root of 21346681 is about 4620.2468548769. The cubic root of 21346681 is about 277.4023399008.

The spelling of 21346681 in words is "twenty-one million, three hundred forty-six thousand, six hundred eighty-one".