21001002101993 has 4 divisors (see below), whose sum is σ = 21068097955668. Its totient is φ = 20933906248320.

The previous prime is 21001002101951. The next prime is 21001002102023. The reversal of 21001002101993 is 39910120010012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7653173674969 + 13347828427024 = 2766437^2 + 3653468^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001002101993 - 2¹⁶ = 21001002036457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21001002101903) 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, 33547926368 + ... + 33547926993.

It is an arithmetic number, because the mean of its divisors is an integer number (5267024488917).

Almost surely, 2^{21001002101993} is an apocalyptic number.

It is an amenable number.

21001002101993 is a deficient number, since it is larger than the sum of its proper divisors (67095853675).

21001002101993 is an equidigital number, since it uses as much as digits as its factorization.

21001002101993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67095853674.

The product of its (nonzero) digits is 972, while the sum is 29.

The spelling of 21001002101993 in words is "twenty-one trillion, one billion, two million, one hundred one thousand, nine hundred ninety-three".