28721423 has 8 divisors (see below), whose sum is σ = 29388000. Its totient is φ = 28061280.

The previous prime is 28721401. The next prime is 28721437. The reversal of 28721423 is 32412782.

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 28721423 - 2¹⁸ = 28459279 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28721453) 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, 8078 + ... + 11076.

It is an arithmetic number, because the mean of its divisors is an integer number (3673500).

Almost surely, 2^28721423 is an apocalyptic number.

28721423 is a deficient number, since it is larger than the sum of its proper divisors (666577).

28721423 is a wasteful number, since it uses less digits than its factorization.

28721423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3217.

The product of its digits is 5376, while the sum is 29.

The square root of 28721423 is about 5359.2371658661. The cubic root of 28721423 is about 306.2447491533.

The spelling of 28721423 in words is "twenty-eight million, seven hundred twenty-one thousand, four hundred twenty-three".