21623522061517 has 2 divisors, whose sum is σ = 21623522061518. Its totient is φ = 21623522061516.

The previous prime is 21623522061499. The next prime is 21623522061571. The reversal of 21623522061517 is 71516022532612.

Together with next prime (21623522061571) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20973734524681 + 649787536836 = 4579709^2 + 806094^2 .

It is a cyclic number.

It is not a de Polignac number, because 21623522061517 - 2¹⁹ = 21623521537229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21623522061577) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10811761030758 + 10811761030759.

It is an arithmetic number, because the mean of its divisors is an integer number (10811761030759).

Almost surely, 2^{21623522061517} is an apocalyptic number.

It is an amenable number.

21623522061517 is a deficient number, since it is larger than the sum of its proper divisors (1).

21623522061517 is an equidigital number, since it uses as much as digits as its factorization.

21623522061517 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 302400, while the sum is 43.

The spelling of 21623522061517 in words is "twenty-one trillion, six hundred twenty-three billion, five hundred twenty-two million, sixty-one thousand, five hundred seventeen".