21021087169 has 4 divisors (see below), whose sum is σ = 21287176960. Its totient is φ = 20754997380.

The previous prime is 21021087151. The next prime is 21021087181. The reversal of 21021087169 is 96178012012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21021087169 - 2⁹ = 21021086657 is a prime.

It is a super-2 number, since 2×21021087169² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21021087119) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 133044777 + ... + 133044934.

It is an arithmetic number, because the mean of its divisors is an integer number (5321794240).

Almost surely, 2^21021087169 is an apocalyptic number.

It is an amenable number.

21021087169 is a deficient number, since it is larger than the sum of its proper divisors (266089791).

21021087169 is an equidigital number, since it uses as much as digits as its factorization.

21021087169 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 266089790.

The product of its (nonzero) digits is 12096, while the sum is 37.

The spelling of 21021087169 in words is "twenty-one billion, twenty-one million, eighty-seven thousand, one hundred sixty-nine".