21688325091 has 24 divisors (see below), whose sum is σ = 32417093280. Its totient is φ = 13956316416.

The previous prime is 21688325077. The next prime is 21688325101. The reversal of 21688325091 is 19052388612.

21688325091 is a `hidden beast` number, since 2 + 1 + 68 + 83 + 2 + 509 + 1 = 666.

It is not a de Polignac number, because 21688325091 - 2⁶ = 21688325027 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21688326091) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1105530 + ... + 1124976.

It is an arithmetic number, because the mean of its divisors is an integer number (1350712220).

Almost surely, 2^21688325091 is an apocalyptic number.

21688325091 is a deficient number, since it is larger than the sum of its proper divisors (10728768189).

21688325091 is a wasteful number, since it uses less digits than its factorization.

21688325091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23755 (or 23752 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 45.

The spelling of 21688325091 in words is "twenty-one billion, six hundred eighty-eight million, three hundred twenty-five thousand, ninety-one".