21400523 has 2 divisors, whose sum is σ = 21400524. Its totient is φ = 21400522.

The previous prime is 21400507. The next prime is 21400583. The reversal of 21400523 is 32500412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21400523 - 2⁴ = 21400507 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21400583) 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, 10700261 + 10700262.

It is an arithmetic number, because the mean of its divisors is an integer number (10700262).

Almost surely, 2^21400523 is an apocalyptic number.

21400523 is a deficient number, since it is larger than the sum of its proper divisors (1).

21400523 is an equidigital number, since it uses as much as digits as its factorization.

21400523 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21400523 is about 4626.0699302972. The cubic root of 21400523 is about 277.6353715513.

Adding to 21400523 its reverse (32500412), we get a palindrome (53900935).

The spelling of 21400523 in words is "twenty-one million, four hundred thousand, five hundred twenty-three".