21620129 has 2 divisors, whose sum is σ = 21620130. Its totient is φ = 21620128.

The previous prime is 21620117. The next prime is 21620153. The reversal of 21620129 is 92102612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18190225 + 3429904 = 4265^2 + 1852^2 .

It is a cyclic number.

It is not a de Polignac number, because 21620129 - 2¹⁶ = 21554593 is a prime.

It is not a weakly prime, because it can be changed into another prime (21620189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10810064 + 10810065.

It is an arithmetic number, because the mean of its divisors is an integer number (10810065).

Almost surely, 2^21620129 is an apocalyptic number.

It is an amenable number.

21620129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21620129 is an equidigital number, since it uses as much as digits as its factorization.

21620129 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 21620129 is about 4649.7450467741. The cubic root of 21620129 is about 278.5818129187.

The spelling of 21620129 in words is "twenty-one million, six hundred twenty thousand, one hundred twenty-nine".