21887429 has 2 divisors, whose sum is σ = 21887430. Its totient is φ = 21887428.

The previous prime is 21887423. The next prime is 21887447. The reversal of 21887429 is 92478812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17623204 + 4264225 = 4198^2 + 2065^2 .

It is a cyclic number.

It is not a de Polignac number, because 21887429 - 2¹² = 21883333 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21887423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10943714 + 10943715.

It is an arithmetic number, because the mean of its divisors is an integer number (10943715).

Almost surely, 2^21887429 is an apocalyptic number.

It is an amenable number.

21887429 is a deficient number, since it is larger than the sum of its proper divisors (1).

21887429 is an equidigital number, since it uses as much as digits as its factorization.

21887429 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 64512, while the sum is 41.

The square root of 21887429 is about 4678.4002607729. The cubic root of 21887429 is about 279.7251938149.

The spelling of 21887429 in words is "twenty-one million, eight hundred eighty-seven thousand, four hundred twenty-nine".