21131771687 has 8 divisors (see below), whose sum is σ = 22758578640. Its totient is φ = 19505148480.

The previous prime is 21131771653. The next prime is 21131771723. The reversal of 21131771687 is 78617713112.

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 21131771687 - 2⁶ = 21131771623 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 (21131771627) 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, 277112 + ... + 345042.

It is an arithmetic number, because the mean of its divisors is an integer number (2844822330).

Almost surely, 2^21131771687 is an apocalyptic number.

21131771687 is a deficient number, since it is larger than the sum of its proper divisors (1626806953).

21131771687 is a wasteful number, since it uses less digits than its factorization.

21131771687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91873.

The product of its digits is 98784, while the sum is 44.

The spelling of 21131771687 in words is "twenty-one billion, one hundred thirty-one million, seven hundred seventy-one thousand, six hundred eighty-seven".