21875545 has 12 divisors (see below), whose sum is σ = 26647596. Its totient is φ = 17239680.

The previous prime is 21875543. The next prime is 21875561. The reversal of 21875545 is 54557812.

It can be written as a sum of positive squares in 6 ways, for example, as 318096 + 21557449 = 564^2 + 4643^2 .

It is not a de Polignac number, because 21875545 - 2¹ = 21875543 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21875543) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 26235 + ... + 27055.

It is an arithmetic number, because the mean of its divisors is an integer number (2220633).

Almost surely, 2^21875545 is an apocalyptic number.

It is an amenable number.

21875545 is a deficient number, since it is larger than the sum of its proper divisors (4772051).

21875545 is an frugal number, since it uses more digits than its factorization.

21875545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 972 (or 899 counting only the distinct ones).

The product of its digits is 56000, while the sum is 37.

The square root of 21875545 is about 4677.1299960553. The cubic root of 21875545 is about 279.6745581124.

The spelling of 21875545 in words is "twenty-one million, eight hundred seventy-five thousand, five hundred forty-five".