21000221993 has 8 divisors (see below), whose sum is σ = 21089405568. Its totient is φ = 20911179744.

The previous prime is 21000221989. The next prime is 21000222007. The reversal of 21000221993 is 39912200012.

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 21000221993 - 2² = 21000221989 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21000221393) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 267980 + ... + 337362.

It is an arithmetic number, because the mean of its divisors is an integer number (2636175696).

Almost surely, 2^21000221993 is an apocalyptic number.

It is an amenable number.

21000221993 is a deficient number, since it is larger than the sum of its proper divisors (89183575).

21000221993 is an equidigital number, since it uses as much as digits as its factorization.

21000221993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70663.

The product of its (nonzero) digits is 1944, while the sum is 29.

The spelling of 21000221993 in words is "twenty-one billion, two hundred twenty-one thousand, nine hundred ninety-three".