21739129 has 2 divisors, whose sum is σ = 21739130. Its totient is φ = 21739128.

The previous prime is 21739103. The next prime is 21739189. The reversal of 21739129 is 92193712.

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., 11209104 + 10530025 = 3348^2 + 3245^2 .

It is a cyclic number.

It is not a de Polignac number, because 21739129 - 2⁷ = 21739001 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21739094 and 21739103.

It is not a weakly prime, because it can be changed into another prime (21739189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10869564 + 10869565.

It is an arithmetic number, because the mean of its divisors is an integer number (10869565).

Almost surely, 2^21739129 is an apocalyptic number.

It is an amenable number.

21739129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21739129 is an equidigital number, since it uses as much as digits as its factorization.

21739129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6804, while the sum is 34.

The square root of 21739129 is about 4662.5238873383. The cubic root of 21739129 is about 279.0919948598.

The spelling of 21739129 in words is "twenty-one million, seven hundred thirty-nine thousand, one hundred twenty-nine".