21641663240567 has 4 divisors (see below), whose sum is σ = 22914702254736. Its totient is φ = 20368624226400.

The previous prime is 21641663240557. The next prime is 21641663240573. The reversal of 21641663240567 is 76504236614612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21641663240567 - 2⁴ = 21641663240551 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 (21641663240557) 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, 636519507059 + ... + 636519507092.

It is an arithmetic number, because the mean of its divisors is an integer number (5728675563684).

Almost surely, 2^{21641663240567} is an apocalyptic number.

21641663240567 is a deficient number, since it is larger than the sum of its proper divisors (1273039014169).

21641663240567 is a wasteful number, since it uses less digits than its factorization.

21641663240567 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1273039014168.

The product of its (nonzero) digits is 8709120, while the sum is 53.

The spelling of 21641663240567 in words is "twenty-one trillion, six hundred forty-one billion, six hundred sixty-three million, two hundred forty thousand, five hundred sixty-seven".