21707150151721 has 4 divisors (see below), whose sum is σ = 21743755801812. Its totient is φ = 21670544501632.

The previous prime is 21707150151683. The next prime is 21707150151769. The reversal of 21707150151721 is 12715105170712.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7823992179600 + 13883157972121 = 2797140^2 + 3726011^2 .

It is a cyclic number.

It is not a de Polignac number, because 21707150151721 - 2³⁷ = 21569711198249 is a prime.

It is a super-2 number, since 2×21707150151721² (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 (21707150851721) 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 3 ways as a sum of consecutive naturals, for example, 18302824156 + ... + 18302825341.

It is an arithmetic number, because the mean of its divisors is an integer number (5435938950453).

Almost surely, 2^{21707150151721} is an apocalyptic number.

It is an amenable number.

21707150151721 is a deficient number, since it is larger than the sum of its proper divisors (36605650091).

21707150151721 is an equidigital number, since it uses as much as digits as its factorization.

21707150151721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36605650090.

The product of its (nonzero) digits is 34300, while the sum is 40.

The spelling of 21707150151721 in words is "twenty-one trillion, seven hundred seven billion, one hundred fifty million, one hundred fifty-one thousand, seven hundred twenty-one".