21064613 has 4 divisors (see below), whose sum is σ = 21079968. Its totient is φ = 21049260.

The previous prime is 21064607. The next prime is 21064621. The reversal of 21064613 is 31646012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21064613 - 2¹⁸ = 20802469 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21064313) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5393 + ... + 8438.

It is an arithmetic number, because the mean of its divisors is an integer number (5269992).

Almost surely, 2^21064613 is an apocalyptic number.

It is an amenable number.

21064613 is a deficient number, since it is larger than the sum of its proper divisors (15355).

21064613 is a wasteful number, since it uses less digits than its factorization.

21064613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15354.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21064613 is about 4589.6201367869. The cubic root of 21064613 is about 276.1750840718.

The spelling of 21064613 in words is "twenty-one million, sixty-four thousand, six hundred thirteen".