21436019 has 4 divisors (see below), whose sum is σ = 23384760. Its totient is φ = 19487280.

The previous prime is 21436013. The next prime is 21436021. The reversal of 21436019 is 91063412.

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

It is a cyclic number.

It is not a de Polignac number, because 21436019 - 2¹⁶ = 21370483 is a prime.

It is a super-2 number, since 2×21436019² = 919005821136722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21436013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 974354 + ... + 974375.

It is an arithmetic number, because the mean of its divisors is an integer number (5846190).

Almost surely, 2^21436019 is an apocalyptic number.

21436019 is a deficient number, since it is larger than the sum of its proper divisors (1948741).

21436019 is a wasteful number, since it uses less digits than its factorization.

21436019 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1948740.

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 21436019 is about 4629.9048586337. The cubic root of 21436019 is about 277.7887868289.

The spelling of 21436019 in words is "twenty-one million, four hundred thirty-six thousand, nineteen".