28138493 has 2 divisors, whose sum is σ = 28138494. Its totient is φ = 28138492.

The previous prime is 28138471. The next prime is 28138511. The reversal of 28138493 is 39483182.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21362884 + 6775609 = 4622^2 + 2603^2 .

It is a cyclic number.

It is not a de Polignac number, because 28138493 - 2²⁴ = 11361277 is a prime.

It is a super-2 number, since 2×28138493² = 1583549576622098, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28138433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14069246 + 14069247.

It is an arithmetic number, because the mean of its divisors is an integer number (14069247).

Almost surely, 2^28138493 is an apocalyptic number.

It is an amenable number.

28138493 is a deficient number, since it is larger than the sum of its proper divisors (1).

28138493 is an equidigital number, since it uses as much as digits as its factorization.

28138493 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 38.

The square root of 28138493 is about 5304.5728385988. The cubic root of 28138493 is about 304.1587243897.

The spelling of 28138493 in words is "twenty-eight million, one hundred thirty-eight thousand, four hundred ninety-three".