21045501 has 16 divisors (see below), whose sum is σ = 31566720. Its totient is φ = 14028876.

The previous prime is 21045487. The next prime is 21045517. The reversal of 21045501 is 10554012.

21045501 is a `hidden beast` number, since 210 + 455 + 0 + 1 = 666.

It is not a de Polignac number, because 21045501 - 2⁵ = 21045469 is a prime.

It is a super-2 number, since 2×21045501² = 885826224682002, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21045301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2625 + ... + 6998.

It is an arithmetic number, because the mean of its divisors is an integer number (1972920).

Almost surely, 2^21045501 is an apocalyptic number.

It is an amenable number.

21045501 is a deficient number, since it is larger than the sum of its proper divisors (10521219).

21045501 is an frugal number, since it uses more digits than its factorization.

21045501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9644 (or 9626 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 21045501 is about 4587.5375747780. The cubic root of 21045501 is about 276.0915339121.

Adding to 21045501 its reverse (10554012), we get a palindrome (31599513).

The spelling of 21045501 in words is "twenty-one million, forty-five thousand, five hundred one".