21301557432721 has 4 divisors (see below), whose sum is σ = 21301604808192. Its totient is φ = 21301510057252.

The previous prime is 21301557432719. The next prime is 21301557432769. The reversal of 21301557432721 is 12723475510312.

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 21301557432721 - 2¹ = 21301557432719 is a prime.

It is a super-3 number, since 3×21301557432721³ (a number of 41 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21301557412721) 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, 23006761 + ... + 23914726.

It is an arithmetic number, because the mean of its divisors is an integer number (5325401202048).

Almost surely, 2^{21301557432721} is an apocalyptic number.

It is an amenable number.

21301557432721 is a deficient number, since it is larger than the sum of its proper divisors (47375471).

21301557432721 is an equidigital number, since it uses as much as digits as its factorization.

21301557432721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47375470.

The product of its (nonzero) digits is 352800, while the sum is 43.

The spelling of 21301557432721 in words is "twenty-one trillion, three hundred one billion, five hundred fifty-seven million, four hundred thirty-two thousand, seven hundred twenty-one".