21606419 has 2 divisors, whose sum is σ = 21606420. Its totient is φ = 21606418.

The previous prime is 21606359. The next prime is 21606437. The reversal of 21606419 is 91460612.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21606419 is a prime.

It is a super-2 number, since 2×21606419² = 933674684007122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21606391 and 21606400.

It is not a weakly prime, because it can be changed into another prime (21606469) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10803209 + 10803210.

It is an arithmetic number, because the mean of its divisors is an integer number (10803210).

Almost surely, 2^21606419 is an apocalyptic number.

21606419 is a deficient number, since it is larger than the sum of its proper divisors (1).

21606419 is an equidigital number, since it uses as much as digits as its factorization.

21606419 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 21606419 is about 4648.2705385982. The cubic root of 21606419 is about 278.5229146536.

The spelling of 21606419 in words is "twenty-one million, six hundred six thousand, four hundred nineteen".