21375171635651 has 4 divisors (see below), whose sum is σ = 21427433669400. Its totient is φ = 21322909601904.

The previous prime is 21375171635641. The next prime is 21375171635693. The reversal of 21375171635651 is 15653617157312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21375171635651 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21375171635593 and 21375171635602.

It is not an unprimeable number, because it can be changed into a prime (21375171635641) 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, 26131016261 + ... + 26131017078.

It is an arithmetic number, because the mean of its divisors is an integer number (5356858417350).

Almost surely, 2^{21375171635651} is an apocalyptic number.

21375171635651 is a deficient number, since it is larger than the sum of its proper divisors (52262033749).

21375171635651 is an equidigital number, since it uses as much as digits as its factorization.

21375171635651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52262033748.

The product of its digits is 3969000, while the sum is 53.

The spelling of 21375171635651 in words is "twenty-one trillion, three hundred seventy-five billion, one hundred seventy-one million, six hundred thirty-five thousand, six hundred fifty-one".