21989129 has 2 divisors, whose sum is σ = 21989130. Its totient is φ = 21989128.

The previous prime is 21989119. The next prime is 21989153. The reversal of 21989129 is 92198912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21715600 + 273529 = 4660^2 + 523^2 .

It is a cyclic number.

It is not a de Polignac number, because 21989129 - 2⁴ = 21989113 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21989119) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10994564 + 10994565.

It is an arithmetic number, because the mean of its divisors is an integer number (10994565).

Almost surely, 2^21989129 is an apocalyptic number.

It is an amenable number.

21989129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21989129 is an equidigital number, since it uses as much as digits as its factorization.

21989129 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23328, while the sum is 41.

The square root of 21989129 is about 4689.2567641365. The cubic root of 21989129 is about 280.1577724773.

The spelling of 21989129 in words is "twenty-one million, nine hundred eighty-nine thousand, one hundred twenty-nine".