21619943 has 2 divisors, whose sum is σ = 21619944. Its totient is φ = 21619942.

The previous prime is 21619933. The next prime is 21619963. The reversal of 21619943 is 34991612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21619943 - 2⁶ = 21619879 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21619933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10809971 + 10809972.

It is an arithmetic number, because the mean of its divisors is an integer number (10809972).

Almost surely, 2^21619943 is an apocalyptic number.

21619943 is a deficient number, since it is larger than the sum of its proper divisors (1).

21619943 is an equidigital number, since it uses as much as digits as its factorization.

21619943 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11664, while the sum is 35.

The square root of 21619943 is about 4649.7250456344. The cubic root of 21619943 is about 278.5810140279.

The spelling of 21619943 in words is "twenty-one million, six hundred nineteen thousand, nine hundred forty-three".