21651551679143 has 2 divisors, whose sum is σ = 21651551679144. Its totient is φ = 21651551679142.

The previous prime is 21651551679137. The next prime is 21651551679169. The reversal of 21651551679143 is 34197615515612.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21651551679143 - 2²⁸ = 21651283243687 is a prime.

It is a super-2 number, since 2×21651551679143² (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 (21651551679643) 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, 10825775839571 + 10825775839572.

It is an arithmetic number, because the mean of its divisors is an integer number (10825775839572).

Almost surely, 2^{21651551679143} is an apocalyptic number.

21651551679143 is a deficient number, since it is larger than the sum of its proper divisors (1).

21651551679143 is an equidigital number, since it uses as much as digits as its factorization.

21651551679143 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6804000, while the sum is 56.

The spelling of 21651551679143 in words is "twenty-one trillion, six hundred fifty-one billion, five hundred fifty-one million, six hundred seventy-nine thousand, one hundred forty-three".