28400905 has 16 divisors (see below), whose sum is σ = 37601424. Its totient is φ = 20459520.

The previous prime is 28400893. The next prime is 28400917. The reversal of 28400905 is 50900482.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (28400893) and next prime (28400917).

It can be written as a sum of positive squares in 8 ways, for example, as 15303744 + 13097161 = 3912^2 + 3619^2 .

It is not a de Polignac number, because 28400905 - 2⁷ = 28400777 is a prime.

It is a super-2 number, since 2×28400905² = 1613222809638050, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2664 + ... + 7993.

It is an arithmetic number, because the mean of its divisors is an integer number (2350089).

Almost surely, 2^28400905 is an apocalyptic number.

28400905 is the 2665-th decagonal number.

It is an amenable number.

28400905 is a deficient number, since it is larger than the sum of its proper divisors (9200519).

28400905 is a wasteful number, since it uses less digits than its factorization.

28400905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10716.

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 28400905 is about 5329.2499472252. The cubic root of 28400905 is about 305.1013011173.

The spelling of 28400905 in words is "twenty-eight million, four hundred thousand, nine hundred five".