21820319 has 2 divisors, whose sum is σ = 21820320. Its totient is φ = 21820318.

The previous prime is 21820301. The next prime is 21820339. The reversal of 21820319 is 91302812.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21820319 is a prime.

It is a super-2 number, since 2×21820319² = 952252642523522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21820339) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10910159 + 10910160.

It is an arithmetic number, because the mean of its divisors is an integer number (10910160).

Almost surely, 2^21820319 is an apocalyptic number.

21820319 is a deficient number, since it is larger than the sum of its proper divisors (1).

21820319 is an equidigital number, since it uses as much as digits as its factorization.

21820319 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 21820319 is about 4671.2224310131. Note that the first 3 decimals coincide. The cubic root of 21820319 is about 279.4390085842.

The spelling of 21820319 in words is "twenty-one million, eight hundred twenty thousand, three hundred nineteen".