21631541650643 has 4 divisors (see below), whose sum is σ = 21631648561440. Its totient is φ = 21631434739848.

The previous prime is 21631541650639. The next prime is 21631541650651. The reversal of 21631541650643 is 34605614513612.

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 21631541650643 - 2² = 21631541650639 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21631541650843) 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, 53151323 + ... + 53556756.

It is an arithmetic number, because the mean of its divisors is an integer number (5407912140360).

Almost surely, 2^{21631541650643} is an apocalyptic number.

21631541650643 is a deficient number, since it is larger than the sum of its proper divisors (106910797).

21631541650643 is a wasteful number, since it uses less digits than its factorization.

21631541650643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106910796.

The product of its (nonzero) digits is 1555200, while the sum is 47.

The spelling of 21631541650643 in words is "twenty-one trillion, six hundred thirty-one billion, five hundred forty-one million, six hundred fifty thousand, six hundred forty-three".