21662129 has 2 divisors, whose sum is σ = 21662130. Its totient is φ = 21662128.

The previous prime is 21662117. The next prime is 21662189. The reversal of 21662129 is 92126612.

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., 21641104 + 21025 = 4652^2 + 145^2 .

It is a cyclic number.

It is not a de Polignac number, because 21662129 - 2⁸ = 21661873 is a prime.

It is not a weakly prime, because it can be changed into another prime (21662189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10831064 + 10831065.

It is an arithmetic number, because the mean of its divisors is an integer number (10831065).

Almost surely, 2^21662129 is an apocalyptic number.

It is an amenable number.

21662129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21662129 is an equidigital number, since it uses as much as digits as its factorization.

21662129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2592, while the sum is 29.

The square root of 21662129 is about 4654.2592321443. The cubic root of 21662129 is about 278.7620904084.

The spelling of 21662129 in words is "twenty-one million, six hundred sixty-two thousand, one hundred twenty-nine".