21169969 has 2 divisors, whose sum is σ = 21169970. Its totient is φ = 21169968.

The previous prime is 21169963. The next prime is 21169979. The reversal of 21169969 is 96996112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17514225 + 3655744 = 4185^2 + 1912^2 .

It is a cyclic number.

It is not a de Polignac number, because 21169969 - 2⁵ = 21169937 is a prime.

It is a super-2 number, since 2×21169969² = 896335174921922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21169963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10584984 + 10584985.

It is an arithmetic number, because the mean of its divisors is an integer number (10584985).

Almost surely, 2^21169969 is an apocalyptic number.

It is an amenable number.

21169969 is a deficient number, since it is larger than the sum of its proper divisors (1).

21169969 is an equidigital number, since it uses as much as digits as its factorization.

21169969 is an evil number, because the sum of its binary digits is even.

The product of its digits is 52488, while the sum is 43.

The square root of 21169969 is about 4601.0834593604. The cubic root of 21169969 is about 276.6347543070.

The spelling of 21169969 in words is "twenty-one million, one hundred sixty-nine thousand, nine hundred sixty-nine".