21101021999 has 6 divisors (see below), whose sum is σ = 21803658480. Its totient is φ = 20420342940.

The previous prime is 21101021987. The next prime is 21101022011. The reversal of 21101021999 is 99912010112.

It is an interprime number because it is at equal distance from previous prime (21101021987) and next prime (21101022011).

It is not a de Polignac number, because 21101021999 - 2³² = 16806054703 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101051999) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 10977719 + ... + 10979640.

It is an arithmetic number, because the mean of its divisors is an integer number (3633943080).

Almost surely, 2^21101021999 is an apocalyptic number.

21101021999 is a deficient number, since it is larger than the sum of its proper divisors (702636481).

21101021999 is an equidigital number, since it uses as much as digits as its factorization.

21101021999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21957421 (or 21957390 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 35.

The spelling of 21101021999 in words is "twenty-one billion, one hundred one million, twenty-one thousand, nine hundred ninety-nine".