21601667653751 has 2 divisors, whose sum is σ = 21601667653752. Its totient is φ = 21601667653750.

The previous prime is 21601667653723. The next prime is 21601667653771. The reversal of 21601667653751 is 15735676610612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21601667653751 - 2³⁴ = 21584487784567 is a prime.

It is a super-2 number, since 2×21601667653751² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21601667653721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10800833826875 + 10800833826876.

It is an arithmetic number, because the mean of its divisors is an integer number (10800833826876).

Almost surely, 2^{21601667653751} is an apocalyptic number.

21601667653751 is a deficient number, since it is larger than the sum of its proper divisors (1).

21601667653751 is an equidigital number, since it uses as much as digits as its factorization.

21601667653751 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9525600, while the sum is 56.

The spelling of 21601667653751 in words is "twenty-one trillion, six hundred one billion, six hundred sixty-seven million, six hundred fifty-three thousand, seven hundred fifty-one".