21742520522731 has 4 divisors (see below), whose sum is σ = 21901225052232. Its totient is φ = 21583815993232.

The previous prime is 21742520522729. The next prime is 21742520522741. The reversal of 21742520522731 is 13722502524712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21742520522731 - 2¹ = 21742520522729 is a prime.

It is a super-2 number, since 2×21742520522731² (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 (21742520522741) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 79352264545 + ... + 79352264818.

It is an arithmetic number, because the mean of its divisors is an integer number (5475306263058).

Almost surely, 2^{21742520522731} is an apocalyptic number.

21742520522731 is a deficient number, since it is larger than the sum of its proper divisors (158704529501).

21742520522731 is a wasteful number, since it uses less digits than its factorization.

21742520522731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158704529500.

The product of its (nonzero) digits is 470400, while the sum is 43.

The spelling of 21742520522731 in words is "twenty-one trillion, seven hundred forty-two billion, five hundred twenty million, five hundred twenty-two thousand, seven hundred thirty-one".