28378581 has 32 divisors (see below), whose sum is σ = 48288768. Its totient is φ = 14394240.

The previous prime is 28378579. The next prime is 28378607. The reversal of 28378581 is 18587382.

It is a happy number.

It is not a de Polignac number, because 28378581 - 2¹ = 28378579 is a prime.

It is a super-2 number, since 2×28378581² = 1610687719147122, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28378541) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8505 + ... + 11361.

It is an arithmetic number, because the mean of its divisors is an integer number (1509024).

Almost surely, 2^28378581 is an apocalyptic number.

28378581 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28378581 is a deficient number, since it is larger than the sum of its proper divisors (19910187).

28378581 is a wasteful number, since it uses less digits than its factorization.

28378581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2921.

The product of its digits is 107520, while the sum is 42.

The square root of 28378581 is about 5327.1550568760. The cubic root of 28378581 is about 305.0213404400.

The spelling of 28378581 in words is "twenty-eight million, three hundred seventy-eight thousand, five hundred eighty-one".