21507532014721 has 4 divisors (see below), whose sum is σ = 21965139078912. Its totient is φ = 21049924950532.

The previous prime is 21507532014713. The next prime is 21507532014763. The reversal of 21507532014721 is 12741023570512.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21507532014721 - 2³ = 21507532014713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21507532014421) 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, 228803532025 + ... + 228803532118.

It is an arithmetic number, because the mean of its divisors is an integer number (5491284769728).

Almost surely, 2^{21507532014721} is an apocalyptic number.

It is an amenable number.

21507532014721 is a deficient number, since it is larger than the sum of its proper divisors (457607064191).

21507532014721 is an equidigital number, since it uses as much as digits as its factorization.

21507532014721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 457607064190.

The product of its (nonzero) digits is 117600, while the sum is 40.

The spelling of 21507532014721 in words is "twenty-one trillion, five hundred seven billion, five hundred thirty-two million, fourteen thousand, seven hundred twenty-one".