21769931 has 2 divisors, whose sum is σ = 21769932. Its totient is φ = 21769930.

The previous prime is 21769907. The next prime is 21769933. The reversal of 21769931 is 13996712.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21769931 - 2¹⁴ = 21753547 is a prime.

It is a super-2 number, since 2×21769931² = 947859791489522, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 21769933, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21769933) 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, 10884965 + 10884966.

It is an arithmetic number, because the mean of its divisors is an integer number (10884966).

Almost surely, 2^21769931 is an apocalyptic number.

21769931 is a deficient number, since it is larger than the sum of its proper divisors (1).

21769931 is an equidigital number, since it uses as much as digits as its factorization.

21769931 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20412, while the sum is 38.

The square root of 21769931 is about 4665.8258647318. The cubic root of 21769931 is about 279.2237470668.

The spelling of 21769931 in words is "twenty-one million, seven hundred sixty-nine thousand, nine hundred thirty-one".