21730901761 has 6 divisors (see below), whose sum is σ = 22454512386. Its totient is φ = 21029904000.

The previous prime is 21730901747. The next prime is 21730901779. The reversal of 21730901761 is 16710903712.

It can be written as a sum of positive squares in only one way, i.e., 19668379536 + 2062522225 = 140244^2 + 45415^2 .

It is not a de Polignac number, because 21730901761 - 2⁹ = 21730901249 is a prime.

It is a super-3 number, since 3×21730901761³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21730901761.

It is not an unprimeable number, because it can be changed into a prime (21730901741) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11305440 + ... + 11307361.

It is an arithmetic number, because the mean of its divisors is an integer number (3742418731).

Almost surely, 2^21730901761 is an apocalyptic number.

It is an amenable number.

21730901761 is a deficient number, since it is larger than the sum of its proper divisors (723610625).

21730901761 is an equidigital number, since it uses as much as digits as its factorization.

21730901761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22612863 (or 22612832 counting only the distinct ones).

The product of its (nonzero) digits is 15876, while the sum is 37.

The spelling of 21730901761 in words is "twenty-one billion, seven hundred thirty million, nine hundred one thousand, seven hundred sixty-one".