21151919 has 2 divisors, whose sum is σ = 21151920. Its totient is φ = 21151918.

The previous prime is 21151877. The next prime is 21151937. The reversal of 21151919 is 91915112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21151919 - 2¹² = 21147823 is a prime.

It is a super-2 number, since 2×21151919² = 894807354765122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21151891 and 21151900.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21151979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10575959 + 10575960.

It is an arithmetic number, because the mean of its divisors is an integer number (10575960).

Almost surely, 2^21151919 is an apocalyptic number.

21151919 is a deficient number, since it is larger than the sum of its proper divisors (1).

21151919 is an equidigital number, since it uses as much as digits as its factorization.

21151919 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 810, while the sum is 29.

The square root of 21151919 is about 4599.1215465565. The cubic root of 21151919 is about 276.5561102442.

The spelling of 21151919 in words is "twenty-one million, one hundred fifty-one thousand, nine hundred nineteen".