21403436 has 12 divisors (see below), whose sum is σ = 38070480. Its totient is φ = 10526160.

The previous prime is 21403433. The next prime is 21403439. The reversal of 21403436 is 63430412.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21403433) and next prime (21403439).

It is not an unprimeable number, because it can be changed into a prime (21403433) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43616 + ... + 44103.

It is an arithmetic number, because the mean of its divisors is an integer number (3172540).

Almost surely, 2^21403436 is an apocalyptic number.

It is an amenable number.

21403436 is a deficient number, since it is larger than the sum of its proper divisors (16667044).

21403436 is a wasteful number, since it uses less digits than its factorization.

21403436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87784 (or 87782 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 21403436 is about 4626.3847656675. The cubic root of 21403436 is about 277.6479680526.

Adding to 21403436 its reverse (63430412), we get a palindrome (84833848).

The spelling of 21403436 in words is "twenty-one million, four hundred three thousand, four hundred thirty-six".