21612769 has 2 divisors, whose sum is σ = 21612770. Its totient is φ = 21612768.

The previous prime is 21612761. The next prime is 21612827. The reversal of 21612769 is 96721612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21270544 + 342225 = 4612^2 + 585^2 .

It is a cyclic number.

It is not a de Polignac number, because 21612769 - 2³ = 21612761 is a prime.

It is a super-2 number, since 2×21612769² = 934223567694722, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (21612761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10806384 + 10806385.

It is an arithmetic number, because the mean of its divisors is an integer number (10806385).

Almost surely, 2^21612769 is an apocalyptic number.

It is an amenable number.

21612769 is a deficient number, since it is larger than the sum of its proper divisors (1).

21612769 is an equidigital number, since it uses as much as digits as its factorization.

21612769 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9072, while the sum is 34.

The square root of 21612769 is about 4648.9535381632. The cubic root of 21612769 is about 278.5501973989.

The spelling of 21612769 in words is "twenty-one million, six hundred twelve thousand, seven hundred sixty-nine".