21613321716765 has 16 divisors (see below), whose sum is σ = 35097453774528. Its totient is φ = 11355058573056.

The previous prime is 21613321716739. The next prime is 21613321716787. The reversal of 21613321716765 is 56761712331612.

It is not a de Polignac number, because 21613321716765 - 2³⁹ = 21063565902877 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10752895372 + ... + 10752897381.

It is an arithmetic number, because the mean of its divisors is an integer number (2193590860908).

Almost surely, 2^{21613321716765} is an apocalyptic number.

It is an amenable number.

21613321716765 is a deficient number, since it is larger than the sum of its proper divisors (13484132057763).

21613321716765 is a wasteful number, since it uses less digits than its factorization.

21613321716765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21505792828.

The product of its digits is 1905120, while the sum is 51.

The spelling of 21613321716765 in words is "twenty-one trillion, six hundred thirteen billion, three hundred twenty-one million, seven hundred sixteen thousand, seven hundred sixty-five".