21770429 has 2 divisors, whose sum is σ = 21770430. Its totient is φ = 21770428.

The previous prime is 21770423. The next prime is 21770431. The reversal of 21770429 is 92407712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11356900 + 10413529 = 3370^2 + 3227^2 .

It is a cyclic number.

It is not a de Polignac number, because 21770429 - 2²⁴ = 4993213 is a prime.

Together with 21770431, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21770395 and 21770404.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21770423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10885214 + 10885215.

It is an arithmetic number, because the mean of its divisors is an integer number (10885215).

Almost surely, 2^21770429 is an apocalyptic number.

It is an amenable number.

21770429 is a deficient number, since it is larger than the sum of its proper divisors (1).

21770429 is an equidigital number, since it uses as much as digits as its factorization.

21770429 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7056, while the sum is 32.

The square root of 21770429 is about 4665.8792311846. The cubic root of 21770429 is about 279.2258761865.

The spelling of 21770429 in words is "twenty-one million, seven hundred seventy thousand, four hundred twenty-nine".