21123463643666 has 8 divisors (see below), whose sum is σ = 32131465824384. Its totient is φ = 10412975035540.

The previous prime is 21123463643663. The next prime is 21123463643699. The reversal of 21123463643666 is 66634636432112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21123463643663) 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, 74378392970 + ... + 74378393253.

It is an arithmetic number, because the mean of its divisors is an integer number (4016433228048).

Almost surely, 2^{21123463643666} is an apocalyptic number.

21123463643666 is a deficient number, since it is larger than the sum of its proper divisors (11008002180718).

21123463643666 is a wasteful number, since it uses less digits than its factorization.

21123463643666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148756786296.

The product of its digits is 13436928, while the sum is 53.

The spelling of 21123463643666 in words is "twenty-one trillion, one hundred twenty-three billion, four hundred sixty-three million, six hundred forty-three thousand, six hundred sixty-six".