28071421 has 4 divisors (see below), whose sum is σ = 32081632. Its totient is φ = 24061212.

The previous prime is 28071413. The next prime is 28071469. The reversal of 28071421 is 12417082.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12417082 = 2 ⋅6208541.

It is not a de Polignac number, because 28071421 - 2³ = 28071413 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28071481) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2005095 + ... + 2005108.

It is an arithmetic number, because the mean of its divisors is an integer number (8020408).

Almost surely, 2^28071421 is an apocalyptic number.

It is an amenable number.

28071421 is a deficient number, since it is larger than the sum of its proper divisors (4010211).

28071421 is an equidigital number, since it uses as much as digits as its factorization.

28071421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4010210.

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 28071421 is about 5298.2469742359. The cubic root of 28071421 is about 303.9168639528.

The spelling of 28071421 in words is "twenty-eight million, seventy-one thousand, four hundred twenty-one".