21420242429 has 4 divisors (see below), whose sum is σ = 21420962940. Its totient is φ = 21419521920.

The previous prime is 21420242407. The next prime is 21420242449. The reversal of 21420242429 is 92424202412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5300131204 + 16120111225 = 72802^2 + 126965^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21420242429 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21420242395 and 21420242404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420242449) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 313652 + ... + 375789.

It is an arithmetic number, because the mean of its divisors is an integer number (5355240735).

Almost surely, 2^21420242429 is an apocalyptic number.

It is an amenable number.

21420242429 is a deficient number, since it is larger than the sum of its proper divisors (720511).

21420242429 is an equidigital number, since it uses as much as digits as its factorization.

21420242429 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 720510.

The product of its (nonzero) digits is 18432, while the sum is 32.

The spelling of 21420242429 in words is "twenty-one billion, four hundred twenty million, two hundred forty-two thousand, four hundred twenty-nine".