28357621 has 4 divisors (see below), whose sum is σ = 29335500. Its totient is φ = 27379744.

The previous prime is 28357607. The next prime is 28357639. The reversal of 28357621 is 12675382.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16695396 + 11662225 = 4086^2 + 3415^2 .

It is a cyclic number.

It is not a de Polignac number, because 28357621 - 2¹³ = 28349429 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 (28357601) 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, 488896 + ... + 488953.

It is an arithmetic number, because the mean of its divisors is an integer number (7333875).

Almost surely, 2^28357621 is an apocalyptic number.

It is an amenable number.

28357621 is a deficient number, since it is larger than the sum of its proper divisors (977879).

28357621 is an equidigital number, since it uses as much as digits as its factorization.

28357621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 977878.

The product of its digits is 20160, while the sum is 34.

The square root of 28357621 is about 5325.1874145423. The cubic root of 28357621 is about 304.9462271949.

The spelling of 28357621 in words is "twenty-eight million, three hundred fifty-seven thousand, six hundred twenty-one".