28421781 has 8 divisors (see below), whose sum is σ = 38088864. Its totient is φ = 18851280.

The previous prime is 28421779. The next prime is 28421801. The reversal of 28421781 is 18712482.

It is a happy number.

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

It is not a de Polignac number, because 28421781 - 2¹ = 28421779 is a prime.

It is a super-2 number, since 2×28421781² = 1615595270423922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28421681) 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, 23455 + ... + 24636.

It is an arithmetic number, because the mean of its divisors is an integer number (4761108).

Almost surely, 2^28421781 is an apocalyptic number.

It is an amenable number.

28421781 is a deficient number, since it is larger than the sum of its proper divisors (9667083).

28421781 is a wasteful number, since it uses less digits than its factorization.

28421781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48291.

The product of its digits is 7168, while the sum is 33.

The square root of 28421781 is about 5331.2082120285. The cubic root of 28421781 is about 305.1760374073.

The spelling of 28421781 in words is "twenty-eight million, four hundred twenty-one thousand, seven hundred eighty-one".