21642799 has 2 divisors, whose sum is σ = 21642800. Its totient is φ = 21642798.

The previous prime is 21642791. The next prime is 21642833. The reversal of 21642799 is 99724612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21642799 - 2³ = 21642791 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21642791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10821399 + 10821400.

It is an arithmetic number, because the mean of its divisors is an integer number (10821400).

Almost surely, 2^21642799 is an apocalyptic number.

21642799 is a deficient number, since it is larger than the sum of its proper divisors (1).

21642799 is an equidigital number, since it uses as much as digits as its factorization.

21642799 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 40.

The square root of 21642799 is about 4652.1821761406. The cubic root of 21642799 is about 278.6791488104.

The spelling of 21642799 in words is "twenty-one million, six hundred forty-two thousand, seven hundred ninety-nine".