28215641 has 4 divisors (see below), whose sum is σ = 29442432. Its totient is φ = 26988852.

The previous prime is 28215619. The next prime is 28215653. The reversal of 28215641 is 14651282.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28215641 is a prime.

It is a super-2 number, since 2×28215641² = 1592244794081762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28215541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 613361 + ... + 613406.

It is an arithmetic number, because the mean of its divisors is an integer number (7360608).

Almost surely, 2^28215641 is an apocalyptic number.

It is an amenable number.

28215641 is a deficient number, since it is larger than the sum of its proper divisors (1226791).

28215641 is a wasteful number, since it uses less digits than its factorization.

28215641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1226790.

The product of its digits is 3840, while the sum is 29.

The square root of 28215641 is about 5311.8397001416. The cubic root of 28215641 is about 304.4364438918.

It can be divided in two parts, 2821 and 5641, that multiplied together give a triangular number (15913261 = T₅₆₄₁).

The spelling of 28215641 in words is "twenty-eight million, two hundred fifteen thousand, six hundred forty-one".