21406742 has 8 divisors (see below), whose sum is σ = 36697296. Its totient is φ = 9174312.

The previous prime is 21406729. The next prime is 21406747. The reversal of 21406742 is 24760412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21406747) 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, 764513 + ... + 764540.

It is an arithmetic number, because the mean of its divisors is an integer number (4587162).

Almost surely, 2^21406742 is an apocalyptic number.

21406742 is a deficient number, since it is larger than the sum of its proper divisors (15290554).

21406742 is a wasteful number, since it uses less digits than its factorization.

21406742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1529062.

The product of its (nonzero) digits is 2688, while the sum is 26.

The square root of 21406742 is about 4626.7420502985. The cubic root of 21406742 is about 277.6622625943.

The spelling of 21406742 in words is "twenty-one million, four hundred six thousand, seven hundred forty-two".