21000202391 has 12 divisors (see below), whose sum is σ = 25865796528. Its totient is φ = 16941339072.

The previous prime is 21000202351. The next prime is 21000202411. The reversal of 21000202391 is 19320200012.

It is not a de Polignac number, because 21000202391 - 2¹⁴ = 21000186007 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 (21000202351) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12604331 + ... + 12605996.

It is an arithmetic number, because the mean of its divisors is an integer number (2155483044).

Almost surely, 2^21000202391 is an apocalyptic number.

21000202391 is a deficient number, since it is larger than the sum of its proper divisors (4865594137).

21000202391 is a wasteful number, since it uses less digits than its factorization.

21000202391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25210358 (or 25210351 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 20.

The spelling of 21000202391 in words is "twenty-one billion, two hundred two thousand, three hundred ninety-one".