21329431 has 2 divisors, whose sum is σ = 21329432. Its totient is φ = 21329430.

The previous prime is 21329401. The next prime is 21329437. The reversal of 21329431 is 13492312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21329431 - 2⁹ = 21328919 is a prime.

It is a super-2 number, since 2×21329431² = 909889253567522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21329396 and 21329405.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21329437) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10664715 + 10664716.

It is an arithmetic number, because the mean of its divisors is an integer number (10664716).

Almost surely, 2^21329431 is an apocalyptic number.

21329431 is a deficient number, since it is larger than the sum of its proper divisors (1).

21329431 is an equidigital number, since it uses as much as digits as its factorization.

21329431 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1296, while the sum is 25.

The square root of 21329431 is about 4618.3796942218. The cubic root of 21329431 is about 277.3275979165.

The spelling of 21329431 in words is "twenty-one million, three hundred twenty-nine thousand, four hundred thirty-one".