21012201191 has 4 divisors (see below), whose sum is σ = 21012495000. Its totient is φ = 21011907384.

The previous prime is 21012201113. The next prime is 21012201211. The reversal of 21012201191 is 19110221012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21012201191 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 (21012201391) 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, 37685 + ... + 208433.

It is an arithmetic number, because the mean of its divisors is an integer number (5253123750).

Almost surely, 2^21012201191 is an apocalyptic number.

21012201191 is a deficient number, since it is larger than the sum of its proper divisors (293809).

21012201191 is a wasteful number, since it uses less digits than its factorization.

21012201191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 293808.

The product of its (nonzero) digits is 72, while the sum is 20.

The spelling of 21012201191 in words is "twenty-one billion, twelve million, two hundred one thousand, one hundred ninety-one".