21154521022666 has 16 divisors (see below), whose sum is σ = 32304047791680. Its totient is φ = 10386887752800.

The previous prime is 21154521022517. The next prime is 21154521022721. The reversal of 21154521022666 is 66622012545112.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 95554110 + ... + 95775241.

It is an arithmetic number, because the mean of its divisors is an integer number (2019002986980).

Almost surely, 2^{21154521022666} is an apocalyptic number.

21154521022666 is a deficient number, since it is larger than the sum of its proper divisors (11149526769014).

21154521022666 is a wasteful number, since it uses less digits than its factorization.

21154521022666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191330349.

The product of its (nonzero) digits is 345600, while the sum is 43.

Adding to 21154521022666 its reverse (66622012545112), we get a palindrome (87776533567778).

The spelling of 21154521022666 in words is "twenty-one trillion, one hundred fifty-four billion, five hundred twenty-one million, twenty-two thousand, six hundred sixty-six".