21931519 has 2 divisors, whose sum is σ = 21931520. Its totient is φ = 21931518.

The previous prime is 21931501. The next prime is 21931523. The reversal of 21931519 is 91513912.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21931519 is a prime.

It is a super-2 number, since 2×21931519² = 961983051294722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21931219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10965759 + 10965760.

It is an arithmetic number, because the mean of its divisors is an integer number (10965760).

Almost surely, 2^21931519 is an apocalyptic number.

21931519 is a deficient number, since it is larger than the sum of its proper divisors (1).

21931519 is an equidigital number, since it uses as much as digits as its factorization.

21931519 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2430, while the sum is 31.

The square root of 21931519 is about 4683.1099709488. The cubic root of 21931519 is about 279.9128938230.

The spelling of 21931519 in words is "twenty-one million, nine hundred thirty-one thousand, five hundred nineteen".