20899523 has 4 divisors (see below), whose sum is σ = 21115080. Its totient is φ = 20683968.

The previous prime is 20899513. The next prime is 20899531. The reversal of 20899523 is 32599802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32599802 = 2 ⋅16299901.

It is a cyclic number.

It is not a de Polignac number, because 20899523 - 2⁴ = 20899507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20899513) 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, 107633 + ... + 107826.

It is an arithmetic number, because the mean of its divisors is an integer number (5278770).

Almost surely, 2^20899523 is an apocalyptic number.

20899523 is a deficient number, since it is larger than the sum of its proper divisors (215557).

20899523 is an equidigital number, since it uses as much as digits as its factorization.

20899523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215556.

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 20899523 is about 4571.5996106396. The cubic root of 20899523 is about 275.4517006291.

The spelling of 20899523 in words is "twenty million, eight hundred ninety-nine thousand, five hundred twenty-three".