21064505 has 16 divisors (see below), whose sum is σ = 31515264. Its totient is φ = 13130880.

The previous prime is 21064499. The next prime is 21064523. The reversal of 21064505 is 50546012.

It is not a de Polignac number, because 21064505 - 2⁸ = 21064249 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26972 + ... + 27741.

It is an arithmetic number, because the mean of its divisors is an integer number (1969704).

Almost surely, 2^21064505 is an apocalyptic number.

It is an amenable number.

21064505 is a deficient number, since it is larger than the sum of its proper divisors (10450759).

21064505 is a wasteful number, since it uses less digits than its factorization.

21064505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54736.

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 21064505 is about 4589.6083710922. The cubic root of 21064505 is about 276.1746120802.

The spelling of 21064505 in words is "twenty-one million, sixty-four thousand, five hundred five".