21245567989 has 2 divisors, whose sum is σ = 21245567990. Its totient is φ = 21245567988.

The previous prime is 21245567957. The next prime is 21245568037. The reversal of 21245567989 is 98976554212.

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., 18555071089 + 2690496900 = 136217^2 + 51870^2 .

It is a cyclic number.

It is not a de Polignac number, because 21245567989 - 2⁵ = 21245567957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21245567909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10622783994 + 10622783995.

It is an arithmetic number, because the mean of its divisors is an integer number (10622783995).

Almost surely, 2^21245567989 is an apocalyptic number.

It is an amenable number.

21245567989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21245567989 is an equidigital number, since it uses as much as digits as its factorization.

21245567989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10886400, while the sum is 58.

The spelling of 21245567989 in words is "twenty-one billion, two hundred forty-five million, five hundred sixty-seven thousand, nine hundred eighty-nine".