28722139 has 4 divisors (see below), whose sum is σ = 28841560. Its totient is φ = 28602720.

The previous prime is 28722137. The next prime is 28722149. The reversal of 28722139 is 93122782.

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 28722139 - 2¹ = 28722137 is a prime.

It is a super-2 number, since 2×28722139² = 1649922537470642, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28722137) 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, 59349 + ... + 59830.

It is an arithmetic number, because the mean of its divisors is an integer number (7210390).

Almost surely, 2^28722139 is an apocalyptic number.

28722139 is a deficient number, since it is larger than the sum of its proper divisors (119421).

28722139 is a wasteful number, since it uses less digits than its factorization.

28722139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 119420.

The product of its digits is 12096, while the sum is 34.

The square root of 28722139 is about 5359.3039660016. The cubic root of 28722139 is about 306.2472939369.

The spelling of 28722139 in words is "twenty-eight million, seven hundred twenty-two thousand, one hundred thirty-nine".