28464721 has 2 divisors, whose sum is σ = 28464722. Its totient is φ = 28464720.

The previous prime is 28464719. The next prime is 28464739. The reversal of 28464721 is 12746482.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 24364096 + 4100625 = 4936^2 + 2025^2 .

It is a cyclic number.

It is not a de Polignac number, because 28464721 - 2¹ = 28464719 is a prime.

Together with 28464719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (28464221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14232360 + 14232361.

It is an arithmetic number, because the mean of its divisors is an integer number (14232361).

Almost surely, 2^28464721 is an apocalyptic number.

It is an amenable number.

28464721 is a deficient number, since it is larger than the sum of its proper divisors (1).

28464721 is an equidigital number, since it uses as much as digits as its factorization.

28464721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21504, while the sum is 34.

The square root of 28464721 is about 5335.2339217695. The cubic root of 28464721 is about 305.3296480627.

The spelling of 28464721 in words is "twenty-eight million, four hundred sixty-four thousand, seven hundred twenty-one".