28449981 has 32 divisors (see below), whose sum is σ = 48646400. Its totient is φ = 16096320.

The previous prime is 28449979. The next prime is 28449989. The reversal of 28449981 is 18994482.

28449981 = T₃₉₈ + T₃₉₉ + ... + T₆₁₅.

28449981 is a `hidden beast` number, since 2 + 84 + 499 + 81 = 666.

It is not a de Polignac number, because 28449981 - 2¹ = 28449979 is a prime.

It is a super-2 number, since 2×28449981² = 1618802837800722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28449989) 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, 19911 + ... + 21291.

It is an arithmetic number, because the mean of its divisors is an integer number (1520200).

Almost surely, 2^28449981 is an apocalyptic number.

28449981 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28449981 is a deficient number, since it is larger than the sum of its proper divisors (20196419).

28449981 is a wasteful number, since it uses less digits than its factorization.

28449981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1506 (or 1500 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The square root of 28449981 is about 5333.8523601615. The cubic root of 28449981 is about 305.2769356064.

The spelling of 28449981 in words is "twenty-eight million, four hundred forty-nine thousand, nine hundred eighty-one".