21129403 has 2 divisors, whose sum is σ = 21129404. Its totient is φ = 21129402.

The previous prime is 21129379. The next prime is 21129439. The reversal of 21129403 is 30492112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21129403 - 2¹³ = 21121211 is a prime.

It is a super-2 number, since 2×21129403² = 892903342272818, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21129803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10564701 + 10564702.

It is an arithmetic number, because the mean of its divisors is an integer number (10564702).

Almost surely, 2^21129403 is an apocalyptic number.

21129403 is a deficient number, since it is larger than the sum of its proper divisors (1).

21129403 is an equidigital number, since it uses as much as digits as its factorization.

21129403 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 21129403 is about 4596.6730360120. The cubic root of 21129403 is about 276.4579450267.

The spelling of 21129403 in words is "twenty-one million, one hundred twenty-nine thousand, four hundred three".