21144975 has 12 divisors (see below), whose sum is σ = 34959816. Its totient is φ = 11277280.

The previous prime is 21144953. The next prime is 21144989. The reversal of 21144975 is 57944112.

It is a happy number.

It is not a de Polignac number, because 21144975 - 2⁷ = 21144847 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 140892 + ... + 141041.

It is an arithmetic number, because the mean of its divisors is an integer number (2913318).

Almost surely, 2^21144975 is an apocalyptic number.

21144975 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21144975 is a deficient number, since it is larger than the sum of its proper divisors (13814841).

21144975 is a wasteful number, since it uses less digits than its factorization.

21144975 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281946 (or 281941 counting only the distinct ones).

The product of its digits is 10080, while the sum is 33.

The square root of 21144975 is about 4598.3665578116. The cubic root of 21144975 is about 276.5258432376.

The spelling of 21144975 in words is "twenty-one million, one hundred forty-four thousand, nine hundred seventy-five".