21738407 has 2 divisors, whose sum is σ = 21738408. Its totient is φ = 21738406.

The previous prime is 21738403. The next prime is 21738419. The reversal of 21738407 is 70483712.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21738407 - 2² = 21738403 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21738403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10869203 + 10869204.

It is an arithmetic number, because the mean of its divisors is an integer number (10869204).

Almost surely, 2^21738407 is an apocalyptic number.

21738407 is a deficient number, since it is larger than the sum of its proper divisors (1).

21738407 is an equidigital number, since it uses as much as digits as its factorization.

21738407 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9408, while the sum is 32.

The square root of 21738407 is about 4662.4464608186. The cubic root of 21738407 is about 279.0889050909.

The spelling of 21738407 in words is "twenty-one million, seven hundred thirty-eight thousand, four hundred seven".