21375145 has 16 divisors (see below), whose sum is σ = 28667520. Its totient is φ = 15164800.

The previous prime is 21375143. The next prime is 21375157. The reversal of 21375145 is 54157312.

It is a happy number.

It is not a de Polignac number, because 21375145 - 2¹ = 21375143 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21375143) 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, 2485 + ... + 6994.

It is an arithmetic number, because the mean of its divisors is an integer number (1791720).

Almost surely, 2^21375145 is an apocalyptic number.

It is an amenable number.

21375145 is a deficient number, since it is larger than the sum of its proper divisors (7292375).

21375145 is a wasteful number, since it uses less digits than its factorization.

21375145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9536.

The product of its digits is 4200, while the sum is 28.

The square root of 21375145 is about 4623.3261836042. The cubic root of 21375145 is about 277.5255826860.

The spelling of 21375145 in words is "twenty-one million, three hundred seventy-five thousand, one hundred forty-five".