28578421 has 2 divisors, whose sum is σ = 28578422. Its totient is φ = 28578420.

The previous prime is 28578409. The next prime is 28578457. The reversal of 28578421 is 12487582.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 24147396 + 4431025 = 4914^2 + 2105^2 .

It is a cyclic number.

It is not a de Polignac number, because 28578421 - 2⁷ = 28578293 is a prime.

It is a super-2 number, since 2×28578421² = 1633452293706482, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28578521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14289210 + 14289211.

It is an arithmetic number, because the mean of its divisors is an integer number (14289211).

Almost surely, 2^28578421 is an apocalyptic number.

It is an amenable number.

28578421 is a deficient number, since it is larger than the sum of its proper divisors (1).

28578421 is an equidigital number, since it uses as much as digits as its factorization.

28578421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 35840, while the sum is 37.

The square root of 28578421 is about 5345.8788800346. The cubic root of 28578421 is about 305.7356460687.

The spelling of 28578421 in words is "twenty-eight million, five hundred seventy-eight thousand, four hundred twenty-one".