21605425422731 has 16 divisors (see below), whose sum is σ = 22246890107904. Its totient is φ = 20970619365024.

The previous prime is 21605425422727. The next prime is 21605425422739. The reversal of 21605425422731 is 13722452450612.

It is a cyclic number.

It is not a de Polignac number, because 21605425422731 - 2² = 21605425422727 is a prime.

It is a super-2 number, since 2×21605425422731² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21605425422739) 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 in 15 ways as a sum of consecutive naturals, for example, 3318500 + ... + 7363646.

It is an arithmetic number, because the mean of its divisors is an integer number (1390430631744).

Almost surely, 2^{21605425422731} is an apocalyptic number.

21605425422731 is a deficient number, since it is larger than the sum of its proper divisors (641464685173).

21605425422731 is a wasteful number, since it uses less digits than its factorization.

21605425422731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4045970.

The product of its (nonzero) digits is 806400, while the sum is 44.

The spelling of 21605425422731 in words is "twenty-one trillion, six hundred five billion, four hundred twenty-five million, four hundred twenty-two thousand, seven hundred thirty-one".