38638721 has 4 divisors (see below), whose sum is σ = 42151344. Its totient is φ = 35126100.

The previous prime is 38638711. The next prime is 38638729. The reversal of 38638721 is 12783683.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 38638721 - 2⁶ = 38638657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (38638729) 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, 1756295 + ... + 1756316.

It is an arithmetic number, because the mean of its divisors is an integer number (10537836).

Almost surely, 2^38638721 is an apocalyptic number.

It is an amenable number.

38638721 is a deficient number, since it is larger than the sum of its proper divisors (3512623).

38638721 is a wasteful number, since it uses less digits than its factorization.

38638721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3512622.

The product of its digits is 48384, while the sum is 38.

The square root of 38638721 is about 6216.0052284405. The cubic root of 38638721 is about 338.0707372694.

The spelling of 38638721 in words is "thirty-eight million, six hundred thirty-eight thousand, seven hundred twenty-one".