21752831 has 2 divisors, whose sum is σ = 21752832. Its totient is φ = 21752830.

The previous prime is 21752791. The next prime is 21752833. The reversal of 21752831 is 13825712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21752831 - 2¹⁴ = 21736447 is a prime.

It is a super-2 number, since 2×21752831² = 946371313029122, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 21752833, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_1374590 and since 21752831 and 1374590 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 21752794 and 21752803.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21752833) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10876415 + 10876416.

It is an arithmetic number, because the mean of its divisors is an integer number (10876416).

Almost surely, 2^21752831 is an apocalyptic number.

21752831 is a deficient number, since it is larger than the sum of its proper divisors (1).

21752831 is an equidigital number, since it uses as much as digits as its factorization.

21752831 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3360, while the sum is 29.

The square root of 21752831 is about 4663.9930317272. The cubic root of 21752831 is about 279.1506190325.

The spelling of 21752831 in words is "twenty-one million, seven hundred fifty-two thousand, eight hundred thirty-one".