21961099 has 2 divisors, whose sum is σ = 21961100. Its totient is φ = 21961098.

The previous prime is 21961097. The next prime is 21961109. The reversal of 21961099 is 99016912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21961099 - 2¹ = 21961097 is a prime.

Together with 21961097, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21961097) 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 as a sum of consecutive naturals, namely, 10980549 + 10980550.

It is an arithmetic number, because the mean of its divisors is an integer number (10980550).

Almost surely, 2^21961099 is an apocalyptic number.

21961099 is a deficient number, since it is larger than the sum of its proper divisors (1).

21961099 is an equidigital number, since it uses as much as digits as its factorization.

21961099 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8748, while the sum is 37.

The square root of 21961099 is about 4686.2670645195. The cubic root of 21961099 is about 280.0386808806.

The spelling of 21961099 in words is "twenty-one million, nine hundred sixty-one thousand, ninety-nine".