20964509 has 4 divisors (see below), whose sum is σ = 20982204. Its totient is φ = 20946816.

The previous prime is 20964497. The next prime is 20964527. The reversal of 20964509 is 90546902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90546902 = 2 ⋅45273451.

It can be written as a sum of positive squares in 2 ways, for example, as 9424900 + 11539609 = 3070^2 + 3397^2 .

It is a cyclic number.

It is not a de Polignac number, because 20964509 - 2⁸ = 20964253 is a prime.

It is a super-2 number, since 2×20964509² = 879021275222162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20964599) 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, 6932 + ... + 9485.

It is an arithmetic number, because the mean of its divisors is an integer number (5245551).

Almost surely, 2^20964509 is an apocalyptic number.

It is an amenable number.

20964509 is a deficient number, since it is larger than the sum of its proper divisors (17695).

20964509 is a wasteful number, since it uses less digits than its factorization.

20964509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17694.

The product of its (nonzero) digits is 19440, while the sum is 35.

The square root of 20964509 is about 4578.7016718716. The cubic root of 20964509 is about 275.7369062234.

The spelling of 20964509 in words is "twenty million, nine hundred sixty-four thousand, five hundred nine".