21580129 has 2 divisors, whose sum is σ = 21580130. Its totient is φ = 21580128.

The previous prime is 21580127. The next prime is 21580133. The reversal of 21580129 is 92108512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20976400 + 603729 = 4580^2 + 777^2 .

It is a cyclic number.

It is not a de Polignac number, because 21580129 - 2¹ = 21580127 is a prime.

Together with 21580127, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21580097 and 21580106.

It is not a weakly prime, because it can be changed into another prime (21580127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10790064 + 10790065.

It is an arithmetic number, because the mean of its divisors is an integer number (10790065).

Almost surely, 2^21580129 is an apocalyptic number.

It is an amenable number.

21580129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21580129 is an equidigital number, since it uses as much as digits as its factorization.

21580129 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 21580129 is about 4645.4417443339. The cubic root of 21580129 is about 278.4099028783.

The spelling of 21580129 in words is "twenty-one million, five hundred eighty thousand, one hundred twenty-nine".