21177436721 has 8 divisors (see below), whose sum is σ = 24208522944. Its totient is φ = 18147785040.

The previous prime is 21177436711. The next prime is 21177436739. The reversal of 21177436721 is 12763477112.

It is a happy number.

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

It is not a de Polignac number, because 21177436721 - 2²² = 21173242417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21177436711) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 326810 + ... + 386211.

It is an arithmetic number, because the mean of its divisors is an integer number (3026065368).

Almost surely, 2^21177436721 is an apocalyptic number.

It is an amenable number.

21177436721 is a deficient number, since it is larger than the sum of its proper divisors (3031086223).

21177436721 is an equidigital number, since it uses as much as digits as its factorization.

21177436721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 717271.

The product of its digits is 98784, while the sum is 41.

The spelling of 21177436721 in words is "twenty-one billion, one hundred seventy-seven million, four hundred thirty-six thousand, seven hundred twenty-one".