21064993 has 2 divisors, whose sum is σ = 21064994. Its totient is φ = 21064992.

The previous prime is 21064957. The next prime is 21065003. The reversal of 21064993 is 39946012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20684304 + 380689 = 4548^2 + 617^2 .

It is a cyclic number.

It is not a de Polignac number, because 21064993 - 2¹³ = 21056801 is a prime.

It is not a weakly prime, because it can be changed into another prime (21064913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10532496 + 10532497.

It is an arithmetic number, because the mean of its divisors is an integer number (10532497).

Almost surely, 2^21064993 is an apocalyptic number.

It is an amenable number.

21064993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21064993 is an equidigital number, since it uses as much as digits as its factorization.

21064993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11664, while the sum is 34.

The square root of 21064993 is about 4589.6615343618. The cubic root of 21064993 is about 276.1767447701.

The spelling of 21064993 in words is "twenty-one million, sixty-four thousand, nine hundred ninety-three".