28661302221 has 4 divisors (see below), whose sum is σ = 38215069632. Its totient is φ = 19107534812.

The previous prime is 28661302213. The next prime is 28661302261. The reversal of 28661302221 is 12220316682.

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 28661302221 - 2³ = 28661302213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28661302261) 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, 4776883701 + ... + 4776883706.

It is an arithmetic number, because the mean of its divisors is an integer number (9553767408).

Almost surely, 2^28661302221 is an apocalyptic number.

It is an amenable number.

28661302221 is a deficient number, since it is larger than the sum of its proper divisors (9553767411).

28661302221 is an equidigital number, since it uses as much as digits as its factorization.

28661302221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9553767410.

The product of its (nonzero) digits is 13824, while the sum is 33.

The spelling of 28661302221 in words is "twenty-eight billion, six hundred sixty-one million, three hundred two thousand, two hundred twenty-one".