28215751 has 4 divisors (see below), whose sum is σ = 28239904. Its totient is φ = 28191600.

The previous prime is 28215743. The next prime is 28215757. The reversal of 28215751 is 15751282.

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

It is a cyclic number.

It is not a de Polignac number, because 28215751 - 2³ = 28215743 is a prime.

It is a super-2 number, since 2×28215751² = 1592257208988002, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28215757) 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, 10230 + ... + 12691.

It is an arithmetic number, because the mean of its divisors is an integer number (7059976).

Almost surely, 2^28215751 is an apocalyptic number.

28215751 is a deficient number, since it is larger than the sum of its proper divisors (24153).

28215751 is a wasteful number, since it uses less digits than its factorization.

28215751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24152.

The product of its digits is 5600, while the sum is 31.

The square root of 28215751 is about 5311.8500543596. The cubic root of 28215751 is about 304.4368395112.

The spelling of 28215751 in words is "twenty-eight million, two hundred fifteen thousand, seven hundred fifty-one".