31728260221 has 16 divisors (see below), whose sum is σ = 36498544128. Its totient is φ = 27017971200.

The previous prime is 31728260197. The next prime is 31728260237. The reversal of 31728260221 is 12206282713.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 31728260221 - 2²¹ = 31726163069 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31728260251) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 645951 + ... + 693331.

It is an arithmetic number, because the mean of its divisors is an integer number (2281159008).

Almost surely, 2^31728260221 is an apocalyptic number.

It is an amenable number.

31728260221 is a deficient number, since it is larger than the sum of its proper divisors (4770283907).

31728260221 is a wasteful number, since it uses less digits than its factorization.

31728260221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48012.

The product of its (nonzero) digits is 16128, while the sum is 34.

The spelling of 31728260221 in words is "thirty-one billion, seven hundred twenty-eight million, two hundred sixty thousand, two hundred twenty-one".