21545429 has 2 divisors, whose sum is σ = 21545430. Its totient is φ = 21545428.

The previous prime is 21545393. The next prime is 21545441. The reversal of 21545429 is 92454512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20160100 + 1385329 = 4490^2 + 1177^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21545429 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21545395 and 21545404.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21545479) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10772714 + 10772715.

It is an arithmetic number, because the mean of its divisors is an integer number (10772715).

Almost surely, 2^21545429 is an apocalyptic number.

It is an amenable number.

21545429 is a deficient number, since it is larger than the sum of its proper divisors (1).

21545429 is an equidigital number, since it uses as much as digits as its factorization.

21545429 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14400, while the sum is 32.

The square root of 21545429 is about 4641.7053978037. The cubic root of 21545429 is about 278.2605987610.

It can be divided in two parts, 2154542 and 9, that multiplied together give a triangular number (19390878 = T₆₂₂₇).

The spelling of 21545429 in words is "twenty-one million, five hundred forty-five thousand, four hundred twenty-nine".