21429869 has 4 divisors (see below), whose sum is σ = 22168860. Its totient is φ = 20690880.

The previous prime is 21429851. The next prime is 21429887. The reversal of 21429869 is 96892412.

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

It is an interprime number because it is at equal distance from previous prime (21429851) and next prime (21429887).

It can be written as a sum of positive squares in 2 ways, for example, as 13801225 + 7628644 = 3715^2 + 2762^2 .

It is a cyclic number.

It is not a de Polignac number, because 21429869 - 2⁸ = 21429613 is a prime.

It is a super-2 number, since 2×21429869² = 918478570714322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21429899) 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, 369452 + ... + 369509.

It is an arithmetic number, because the mean of its divisors is an integer number (5542215).

Almost surely, 2^21429869 is an apocalyptic number.

21429869 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21429869 is a deficient number, since it is larger than the sum of its proper divisors (738991).

21429869 is an equidigital number, since it uses as much as digits as its factorization.

21429869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 738990.

The product of its digits is 62208, while the sum is 41.

The square root of 21429869 is about 4629.2406504739. The cubic root of 21429869 is about 277.7622183937.

The spelling of 21429869 in words is "twenty-one million, four hundred twenty-nine thousand, eight hundred sixty-nine".