28207561 has 2 divisors, whose sum is σ = 28207562. Its totient is φ = 28207560.

The previous prime is 28207547. The next prime is 28207643. The reversal of 28207561 is 16570282.

28207561 = 3755² + 3756².

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14107536 + 14100025 = 3756^2 + 3755^2 .

It is a cyclic number.

It is not a de Polignac number, because 28207561 - 2⁷ = 28207433 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (28207511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14103780 + 14103781.

It is an arithmetic number, because the mean of its divisors is an integer number (14103781).

Almost surely, 2^28207561 is an apocalyptic number.

28207561 is the 3756-th centered square number.

It is an amenable number.

28207561 is a deficient number, since it is larger than the sum of its proper divisors (1).

28207561 is an equidigital number, since it uses as much as digits as its factorization.

28207561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 28207561 is about 5311.0790805636. The cubic root of 28207561 is about 304.4073810361.

The spelling of 28207561 in words is "twenty-eight million, two hundred seven thousand, five hundred sixty-one".