21408730 has 16 divisors (see below), whose sum is σ = 44040960. Its totient is φ = 7340112.

The previous prime is 21408727. The next prime is 21408733. The reversal of 21408730 is 3780412.

It is an interprime number because it is at equal distance from previous prime (21408727) and next prime (21408733).

It is a junction number, because it is equal to n+sod(n) for n = 21408695 and 21408704.

It is not an unprimeable number, because it can be changed into a prime (21408733) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 152850 + ... + 152989.

It is an arithmetic number, because the mean of its divisors is an integer number (2752560).

Almost surely, 2^21408730 is an apocalyptic number.

21408730 is an abundant number, since it is smaller than the sum of its proper divisors (22632230).

21408730 is a wasteful number, since it uses less digits than its factorization.

21408730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305853.

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

The square root of 21408730 is about 4626.9568833089. The cubic root of 21408730 is about 277.6708576356.

The spelling of 21408730 in words is "twenty-one million, four hundred eight thousand, seven hundred thirty".