21145744 has 20 divisors (see below), whose sum is σ = 41466096. Its totient is φ = 10444832.

The previous prime is 21145741. The next prime is 21145753. The reversal of 21145744 is 44754112.

It is not an unprimeable number, because it can be changed into a prime (21145741) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6634 + ... + 9289.

Almost surely, 2^21145744 is an apocalyptic number.

It is an amenable number.

21145744 is a deficient number, since it is larger than the sum of its proper divisors (20320352).

21145744 is a wasteful number, since it uses less digits than its factorization.

21145744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16014 (or 16008 counting only the distinct ones).

The product of its digits is 4480, while the sum is 28.

The square root of 21145744 is about 4598.4501736998. The cubic root of 21145744 is about 276.5291954256.

Adding to 21145744 its reverse (44754112), we get a palindrome (65899856).

The spelling of 21145744 in words is "twenty-one million, one hundred forty-five thousand, seven hundred forty-four".