21012001993 has 8 divisors (see below), whose sum is σ = 21376193760. Its totient is φ = 20648078880.

The previous prime is 21012001991. The next prime is 21012002009. The reversal of 21012001993 is 39910021012.

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

It is a cyclic number.

It is not a de Polignac number, because 21012001993 - 2¹ = 21012001991 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21012001991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 93933 + ... + 225493.

It is an arithmetic number, because the mean of its divisors is an integer number (2672024220).

Almost surely, 2^21012001993 is an apocalyptic number.

It is an amenable number.

21012001993 is a deficient number, since it is larger than the sum of its proper divisors (364191767).

21012001993 is a wasteful number, since it uses less digits than its factorization.

21012001993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134327.

The product of its (nonzero) digits is 972, while the sum is 28.

The spelling of 21012001993 in words is "twenty-one billion, twelve million, one thousand, nine hundred ninety-three".