28661891 has 2 divisors, whose sum is σ = 28661892. Its totient is φ = 28661890.

The previous prime is 28661879. The next prime is 28661903. The reversal of 28661891 is 19816682.

It is a balanced prime because it is at equal distance from previous prime (28661879) and next prime (28661903).

It is a cyclic number.

It is not a de Polignac number, because 28661891 - 2¹⁰ = 28660867 is a prime.

It is not a weakly prime, because it can be changed into another prime (28663891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14330945 + 14330946.

It is an arithmetic number, because the mean of its divisors is an integer number (14330946).

Almost surely, 2^28661891 is an apocalyptic number.

28661891 is a deficient number, since it is larger than the sum of its proper divisors (1).

28661891 is an equidigital number, since it uses as much as digits as its factorization.

28661891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 41.

The square root of 28661891 is about 5353.6801361307. The cubic root of 28661891 is about 306.0330143655.

The spelling of 28661891 in words is "twenty-eight million, six hundred sixty-one thousand, eight hundred ninety-one".