28020644 has 6 divisors (see below), whose sum is σ = 49036134. Its totient is φ = 14010320.

The previous prime is 28020631. The next prime is 28020659. The reversal of 28020644 is 44602082.

It can be written as a sum of positive squares in only one way, i.e., 25000000 + 3020644 = 5000^2 + 1738^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3502577 + ... + 3502584.

It is an arithmetic number, because the mean of its divisors is an integer number (8172689).

Almost surely, 2^28020644 is an apocalyptic number.

It is an amenable number.

28020644 is a deficient number, since it is larger than the sum of its proper divisors (21015490).

28020644 is a wasteful number, since it uses less digits than its factorization.

28020644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7005165 (or 7005163 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 26.

The square root of 28020644 is about 5293.4529373557. The cubic root of 28020644 is about 303.7335066434.

The spelling of 28020644 in words is "twenty-eight million, twenty thousand, six hundred forty-four".