21407638 has 16 divisors (see below), whose sum is σ = 36877824. Its totient is φ = 9129960.

The previous prime is 21407629. The next prime is 21407647. The reversal of 21407638 is 83670412.

It is an interprime number because it is at equal distance from previous prime (21407629) and next prime (21407647).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 670 + ... + 6577.

It is an arithmetic number, because the mean of its divisors is an integer number (2304864).

Almost surely, 2^21407638 is an apocalyptic number.

21407638 is a deficient number, since it is larger than the sum of its proper divisors (15470186).

21407638 is a wasteful number, since it uses less digits than its factorization.

21407638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7467.

The product of its (nonzero) digits is 8064, while the sum is 31.

The square root of 21407638 is about 4626.8388776788. The cubic root of 21407638 is about 277.6661364816. Note that the first 3 decimals are identical.

The spelling of 21407638 in words is "twenty-one million, four hundred seven thousand, six hundred thirty-eight".