21045145 has 16 divisors (see below), whose sum is σ = 27682560. Its totient is φ = 15232000.

The previous prime is 21045139. The next prime is 21045149. The reversal of 21045145 is 54154012.

It is not a de Polignac number, because 21045145 - 2³ = 21045137 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21045149) 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, 12345 + ... + 13945.

It is an arithmetic number, because the mean of its divisors is an integer number (1730160).

Almost surely, 2^21045145 is an apocalyptic number.

It is an amenable number.

21045145 is a deficient number, since it is larger than the sum of its proper divisors (6637415).

21045145 is a wasteful number, since it uses less digits than its factorization.

21045145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1856.

The product of its (nonzero) digits is 800, while the sum is 22.

The square root of 21045145 is about 4587.4987738418. The cubic root of 21045145 is about 276.0899771401.

Adding to 21045145 its reverse (54154012), we get a palindrome (75199157).

The spelling of 21045145 in words is "twenty-one million, forty-five thousand, one hundred forty-five".