21471315721 has 8 divisors (see below), whose sum is σ = 21628776960. Its totient is φ = 21314401152.

The previous prime is 21471315667. The next prime is 21471315727. The reversal of 21471315721 is 12751317412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21471315721 - 2⁹ = 21471315209 is a prime.

It is a super-2 number, since 2×21471315721² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21471315727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57661 + ... + 215098.

It is an arithmetic number, because the mean of its divisors is an integer number (2703597120).

Almost surely, 2^21471315721 is an apocalyptic number.

It is an amenable number.

21471315721 is a deficient number, since it is larger than the sum of its proper divisors (157461239).

21471315721 is a wasteful number, since it uses less digits than its factorization.

21471315721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 273335.

The product of its digits is 11760, while the sum is 34.

The spelling of 21471315721 in words is "twenty-one billion, four hundred seventy-one million, three hundred fifteen thousand, seven hundred twenty-one".