21061619 has 2 divisors, whose sum is σ = 21061620. Its totient is φ = 21061618.

The previous prime is 21061613. The next prime is 21061639. The reversal of 21061619 is 91616012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21061619 - 2⁴ = 21061603 is a prime.

It is a super-2 number, since 2×21061619² = 887183589802322, which contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21061613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10530809 + 10530810.

It is an arithmetic number, because the mean of its divisors is an integer number (10530810).

Almost surely, 2^21061619 is an apocalyptic number.

21061619 is a deficient number, since it is larger than the sum of its proper divisors (1).

21061619 is an equidigital number, since it uses as much as digits as its factorization.

21061619 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 21061619 is about 4589.2939544117. The cubic root of 21061619 is about 276.1619988187.

The spelling of 21061619 in words is "twenty-one million, sixty-one thousand, six hundred nineteen".