21357929 has 2 divisors, whose sum is σ = 21357930. Its totient is φ = 21357928.

The previous prime is 21357923. The next prime is 21357937. The reversal of 21357929 is 92975312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18939904 + 2418025 = 4352^2 + 1555^2 .

It is a cyclic number.

It is not a de Polignac number, because 21357929 - 2⁴ = 21357913 is a prime.

It is a super-2 number, since 2×21357929² = 912322262338082, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21357892 and 21357901.

It is not a weakly prime, because it can be changed into another prime (21357923) 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, 10678964 + 10678965.

It is an arithmetic number, because the mean of its divisors is an integer number (10678965).

Almost surely, 2^21357929 is an apocalyptic number.

It is an amenable number.

21357929 is a deficient number, since it is larger than the sum of its proper divisors (1).

21357929 is an equidigital number, since it uses as much as digits as its factorization.

21357929 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34020, while the sum is 38.

The square root of 21357929 is about 4621.4639455480. The cubic root of 21357929 is about 277.4510543223.

The spelling of 21357929 in words is "twenty-one million, three hundred fifty-seven thousand, nine hundred twenty-nine".