21087403 has 2 divisors, whose sum is σ = 21087404. Its totient is φ = 21087402.

The previous prime is 21087401. The next prime is 21087419. The reversal of 21087403 is 30478012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21087403 - 2¹ = 21087401 is a prime.

Together with 21087401, it forms a pair of twin primes.

It is equal to p_1335148 and since 21087403 and 1335148 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21087401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10543701 + 10543702.

It is an arithmetic number, because the mean of its divisors is an integer number (10543702).

Almost surely, 2^21087403 is an apocalyptic number.

21087403 is a deficient number, since it is larger than the sum of its proper divisors (1).

21087403 is an equidigital number, since it uses as much as digits as its factorization.

21087403 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 21087403 is about 4592.1022418931. The cubic root of 21087403 is about 276.2746469686.

The spelling of 21087403 in words is "twenty-one million, eighty-seven thousand, four hundred three".