28993639 has 8 divisors (see below), whose sum is σ = 31847040. Its totient is φ = 26273016.

The previous prime is 28993637. The next prime is 28993693. The reversal of 28993639 is 93639982.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28993639 - 2¹ = 28993637 is a prime.

It is a super-2 number, since 2×28993639² = 1681262204924642, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 28993592 and 28993601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28993637) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32737 + ... + 33610.

It is an arithmetic number, because the mean of its divisors is an integer number (3980880).

Almost surely, 2^28993639 is an apocalyptic number.

28993639 is a deficient number, since it is larger than the sum of its proper divisors (2853401).

28993639 is a wasteful number, since it uses less digits than its factorization.

28993639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66389.

The product of its digits is 629856, while the sum is 49.

The square root of 28993639 is about 5384.5741707214. The cubic root of 28993639 is about 307.2092176992.

The spelling of 28993639 in words is "twenty-eight million, nine hundred ninety-three thousand, six hundred thirty-nine".