21025744 has 10 divisors (see below), whose sum is σ = 40737410. Its totient is φ = 10512864.

The previous prime is 21025729. The next prime is 21025751. The reversal of 21025744 is 44752012.

It can be written as a sum of positive squares in only one way, i.e., 20142144 + 883600 = 4488^2 + 940^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 657039 + ... + 657070.

It is an arithmetic number, because the mean of its divisors is an integer number (4073741).

Almost surely, 2^21025744 is an apocalyptic number.

It is an amenable number.

21025744 is a deficient number, since it is larger than the sum of its proper divisors (19711666).

21025744 is a wasteful number, since it uses less digits than its factorization.

21025744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1314117 (or 1314111 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 25.

The square root of 21025744 is about 4585.3837353050. The cubic root of 21025744 is about 276.0051108764.

Adding to 21025744 its reverse (44752012), we get a palindrome (65777756).

The spelling of 21025744 in words is "twenty-one million, twenty-five thousand, seven hundred forty-four".