21799501 has 2 divisors, whose sum is σ = 21799502. Its totient is φ = 21799500.

The previous prime is 21799499. The next prime is 21799507. The reversal of 21799501 is 10599712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19811401 + 1988100 = 4451^2 + 1410^2 .

It is a cyclic number.

It is not a de Polignac number, because 21799501 - 2¹ = 21799499 is a prime.

Together with 21799499, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21799507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10899750 + 10899751.

It is an arithmetic number, because the mean of its divisors is an integer number (10899751).

Almost surely, 2^21799501 is an apocalyptic number.

It is an amenable number.

21799501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21799501 is an equidigital number, since it uses as much as digits as its factorization.

21799501 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5670, while the sum is 34.

The square root of 21799501 is about 4668.9935746368. The cubic root of 21799501 is about 279.3501126594.

The spelling of 21799501 in words is "twenty-one million, seven hundred ninety-nine thousand, five hundred one".