21064651 has 4 divisors (see below), whose sum is σ = 21204304. Its totient is φ = 20925000.

The previous prime is 21064627. The next prime is 21064679. The reversal of 21064651 is 15646012.

21064651 = T₄₉ + T₅₀ + ... + T₅₀₁.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21064651 - 2⁷ = 21064523 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21064621) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 69600 + ... + 69901.

It is an arithmetic number, because the mean of its divisors is an integer number (5301076).

Almost surely, 2^21064651 is an apocalyptic number.

21064651 is a deficient number, since it is larger than the sum of its proper divisors (139653).

21064651 is a wasteful number, since it uses less digits than its factorization.

21064651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139652.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21064651 is about 4589.6242765612. The cubic root of 21064651 is about 276.1752501425.

The spelling of 21064651 in words is "twenty-one million, sixty-four thousand, six hundred fifty-one".