21371687751 has 16 divisors (see below), whose sum is σ = 30187987200. Its totient is φ = 13402489728.

The previous prime is 21371687741. The next prime is 21371687761. The reversal of 21371687751 is 15778617312.

It is an interprime number because it is at equal distance from previous prime (21371687741) and next prime (21371687761).

It is not a de Polignac number, because 21371687751 - 2¹¹ = 21371685703 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21371687751.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21371687731) 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 15 ways as a sum of consecutive naturals, for example, 15681 + ... + 207338.

It is an arithmetic number, because the mean of its divisors is an integer number (1886749200).

Almost surely, 2^21371687751 is an apocalyptic number.

21371687751 is a deficient number, since it is larger than the sum of its proper divisors (8816299449).

21371687751 is a wasteful number, since it uses less digits than its factorization.

21371687751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 224918.

The product of its digits is 493920, while the sum is 48.

The spelling of 21371687751 in words is "twenty-one billion, three hundred seventy-one million, six hundred eighty-seven thousand, seven hundred fifty-one".