20521429 has 2 divisors, whose sum is σ = 20521430. Its totient is φ = 20521428.

The previous prime is 20521409. The next prime is 20521447. The reversal of 20521429 is 92412502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20520900 + 529 = 4530^2 + 23^2 .

It is a cyclic number.

It is not a de Polignac number, because 20521429 - 2⁷ = 20521301 is a prime.

It is a super-2 number, since 2×20521429² = 842258096404082, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20521409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10260714 + 10260715.

It is an arithmetic number, because the mean of its divisors is an integer number (10260715).

Almost surely, 2^20521429 is an apocalyptic number.

It is an amenable number.

20521429 is a deficient number, since it is larger than the sum of its proper divisors (1).

20521429 is an equidigital number, since it uses as much as digits as its factorization.

20521429 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 20521429 is about 4530.0583881447. The cubic root of 20521429 is about 273.7805131296.

It can be divided in two parts, 2052 and 1429, that added together give a square (3481 = 59²).

The spelling of 20521429 in words is "twenty million, five hundred twenty-one thousand, four hundred twenty-nine".