20521723 has 2 divisors, whose sum is σ = 20521724. Its totient is φ = 20521722.

The previous prime is 20521679. The next prime is 20521733. The reversal of 20521723 is 32712502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20521723 - 2¹³ = 20513531 is a prime.

It is a super-2 number, since 2×20521723² = 842282229777458, which contains 22 as substring.

It is equal to p_1301566 and since 20521723 and 1301566 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 20521694 and 20521703.

It is not a weakly prime, because it can be changed into another prime (20521733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10260861 + 10260862.

It is an arithmetic number, because the mean of its divisors is an integer number (10260862).

Almost surely, 2^20521723 is an apocalyptic number.

20521723 is a deficient number, since it is larger than the sum of its proper divisors (1).

20521723 is an equidigital number, since it uses as much as digits as its factorization.

20521723 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 20521723 is about 4530.0908379413. The cubic root of 20521723 is about 273.7818205610.

It can be divided in two parts, 2052172 and 3, that multiplied together give a palindrome (6156516).

The spelling of 20521723 in words is "twenty million, five hundred twenty-one thousand, seven hundred twenty-three".