21351619 has 2 divisors, whose sum is σ = 21351620. Its totient is φ = 21351618.

The previous prime is 21351601. The next prime is 21351637. The reversal of 21351619 is 91615312.

It is a balanced prime because it is at equal distance from previous prime (21351601) and next prime (21351637).

It is a cyclic number.

It is not a de Polignac number, because 21351619 - 2¹¹ = 21349571 is a prime.

It is a super-2 number, since 2×21351619² = 911783267842322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21351679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10675809 + 10675810.

It is an arithmetic number, because the mean of its divisors is an integer number (10675810).

Almost surely, 2^21351619 is an apocalyptic number.

21351619 is a deficient number, since it is larger than the sum of its proper divisors (1).

21351619 is an equidigital number, since it uses as much as digits as its factorization.

21351619 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1620, while the sum is 28.

The square root of 21351619 is about 4620.7812110075. The cubic root of 21351619 is about 277.4237281929.

The spelling of 21351619 in words is "twenty-one million, three hundred fifty-one thousand, six hundred nineteen".