21191961653669 has 4 divisors (see below), whose sum is σ = 21196259359200. Its totient is φ = 21187663948140.

The previous prime is 21191961653593. The next prime is 21191961653701. The reversal of 21191961653669 is 96635616919112.

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 a de Polignac number, because none of the positive numbers 2^k-21191961653669 is a prime.

It is a super-2 number, since 2×21191961653669² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21191961658669) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2148845369 + ... + 2148855230.

It is an arithmetic number, because the mean of its divisors is an integer number (5299064839800).

Almost surely, 2^{21191961653669} is an apocalyptic number.

It is an amenable number.

21191961653669 is a deficient number, since it is larger than the sum of its proper divisors (4297705531).

21191961653669 is an equidigital number, since it uses as much as digits as its factorization.

21191961653669 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4297705530.

The product of its digits is 28343520, while the sum is 65.

The spelling of 21191961653669 in words is "twenty-one trillion, one hundred ninety-one billion, nine hundred sixty-one million, six hundred fifty-three thousand, six hundred sixty-nine".