21053145 has 16 divisors (see below), whose sum is σ = 33800832. Its totient is φ = 11189760.

The previous prime is 21053129. The next prime is 21053173. The reversal of 21053145 is 54135012.

It is not a de Polignac number, because 21053145 - 2⁴ = 21053129 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2409 + ... + 6921.

It is an arithmetic number, because the mean of its divisors is an integer number (2112552).

Almost surely, 2^21053145 is an apocalyptic number.

It is an amenable number.

21053145 is a deficient number, since it is larger than the sum of its proper divisors (12747687).

21053145 is a wasteful number, since it uses less digits than its factorization.

21053145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4832.

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 21053145 is about 4588.3706258322. The cubic root of 21053145 is about 276.1249565460.

Adding to 21053145 its reverse (54135012), we get a palindrome (75188157).

It can be divided in two parts, 210 and 53145, that multiplied together give a triangular number (11160450 = T₄₇₂₄).

The spelling of 21053145 in words is "twenty-one million, fifty-three thousand, one hundred forty-five".