21954019 has 2 divisors, whose sum is σ = 21954020. Its totient is φ = 21954018.

The previous prime is 21954011. The next prime is 21954047. The reversal of 21954019 is 91045912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21954019 - 2³ = 21954011 is a prime.

It is a super-2 number, since 2×21954019² = 963957900504722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21954011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10977009 + 10977010.

It is an arithmetic number, because the mean of its divisors is an integer number (10977010).

Almost surely, 2^21954019 is an apocalyptic number.

21954019 is a deficient number, since it is larger than the sum of its proper divisors (1).

21954019 is an equidigital number, since it uses as much as digits as its factorization.

21954019 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 21954019 is about 4685.5116049371. The cubic root of 21954019 is about 280.0085839205.

The spelling of 21954019 in words is "twenty-one million, nine hundred fifty-four thousand, nineteen".