21654386642990 has 16 divisors (see below), whose sum is σ = 39080740016880. Its totient is φ = 8638900421760.

The previous prime is 21654386642971. The next prime is 21654386643017. The reversal of 21654386642990 is 9924668345612.

It is a happy number.

It is a super-2 number, since 2×21654386642990² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2856775451 + ... + 2856783030.

It is an arithmetic number, because the mean of its divisors is an integer number (2442546251055).

Almost surely, 2^{21654386642990} is an apocalyptic number.

21654386642990 is a deficient number, since it is larger than the sum of its proper divisors (17426353373890).

21654386642990 is a wasteful number, since it uses less digits than its factorization.

21654386642990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5713558867.

The product of its (nonzero) digits is 134369280, while the sum is 65.

The spelling of 21654386642990 in words is "twenty-one trillion, six hundred fifty-four billion, three hundred eighty-six million, six hundred forty-two thousand, nine hundred ninety".