28720819 has 2 divisors, whose sum is σ = 28720820. Its totient is φ = 28720818.

The previous prime is 28720801. The next prime is 28720831. The reversal of 28720819 is 91802782.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 28720819 - 2¹³ = 28712627 is a prime.

It is a super-2 number, since 2×28720819² = 1649770888061522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (28720919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14360409 + 14360410.

It is an arithmetic number, because the mean of its divisors is an integer number (14360410).

Almost surely, 2^28720819 is an apocalyptic number.

28720819 is a deficient number, since it is larger than the sum of its proper divisors (1).

28720819 is an equidigital number, since it uses as much as digits as its factorization.

28720819 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 28720819 is about 5359.1808142663. The cubic root of 28720819 is about 306.2426024036.

The spelling of 28720819 in words is "twenty-eight million, seven hundred twenty thousand, eight hundred nineteen".