21664401043351 has 32 divisors (see below), whose sum is σ = 24293136833280. Its totient is φ = 19146446668800.

The previous prime is 21664401043333. The next prime is 21664401043367. The reversal of 21664401043351 is 15334010446612.

It is not a de Polignac number, because 21664401043351 - 2⁵ = 21664401043319 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21664401043651) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4051690060 + ... + 4051695406.

It is an arithmetic number, because the mean of its divisors is an integer number (759160526040).

Almost surely, 2^{21664401043351} is an apocalyptic number.

21664401043351 is a deficient number, since it is larger than the sum of its proper divisors (2628735789929).

21664401043351 is a wasteful number, since it uses less digits than its factorization.

21664401043351 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11935.

The product of its (nonzero) digits is 207360, while the sum is 40.

Adding to 21664401043351 its reverse (15334010446612), we get a palindrome (36998411489963).

The spelling of 21664401043351 in words is "twenty-one trillion, six hundred sixty-four billion, four hundred one million, forty-three thousand, three hundred fifty-one".