21011745 has 48 divisors (see below), whose sum is σ = 36957888. Its totient is φ = 10183680.

The previous prime is 21011741. The next prime is 21011759. The reversal of 21011745 is 54711012.

It is a happy number.

It is not a de Polignac number, because 21011745 - 2² = 21011741 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21011741) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 160330 + ... + 160460.

It is an arithmetic number, because the mean of its divisors is an integer number (769956).

Almost surely, 2^21011745 is an apocalyptic number.

It is an amenable number.

21011745 is a deficient number, since it is larger than the sum of its proper divisors (15946143).

21011745 is a wasteful number, since it uses less digits than its factorization.

21011745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210 (or 193 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 21.

The square root of 21011745 is about 4583.8570003873. The cubic root of 21011745 is about 275.9438422816.

Adding to 21011745 its reverse (54711012), we get a palindrome (75722757).

The spelling of 21011745 in words is "twenty-one million, eleven thousand, seven hundred forty-five".