21643136654 has 4 divisors (see below), whose sum is σ = 32464704984. Its totient is φ = 10821568326.

The previous prime is 21643136651. The next prime is 21643136663. The reversal of 21643136654 is 45663134612.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21643136651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5410784162 + ... + 5410784165.

It is an arithmetic number, because the mean of its divisors is an integer number (8116176246).

Almost surely, 2^21643136654 is an apocalyptic number.

21643136654 is a deficient number, since it is larger than the sum of its proper divisors (10821568330).

21643136654 is a wasteful number, since it uses less digits than its factorization.

21643136654 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10821568329.

The product of its digits is 311040, while the sum is 41.

The spelling of 21643136654 in words is "twenty-one billion, six hundred forty-three million, one hundred thirty-six thousand, six hundred fifty-four".