28507731 has 16 divisors (see below), whose sum is σ = 43603968. Its totient is φ = 16228800.

The previous prime is 28507729. The next prime is 28507747. The reversal of 28507731 is 13770582.

It is not a de Polignac number, because 28507731 - 2¹ = 28507729 is a prime.

It is a super-2 number, since 2×28507731² = 1625381453536722, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 28507692 and 28507701.

It is not an unprimeable number, because it can be changed into a prime (28507231) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3486 + ... + 8316.

It is an arithmetic number, because the mean of its divisors is an integer number (2725248).

Almost surely, 2^28507731 is an apocalyptic number.

28507731 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

28507731 is a deficient number, since it is larger than the sum of its proper divisors (15096237).

28507731 is a wasteful number, since it uses less digits than its factorization.

28507731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5122.

The product of its (nonzero) digits is 11760, while the sum is 33.

The square root of 28507731 is about 5339.2631514096. The cubic root of 28507731 is about 305.4833543468.

The spelling of 28507731 in words is "twenty-eight million, five hundred seven thousand, seven hundred thirty-one".