21640038 has 32 divisors (see below), whose sum is σ = 49864704. Its totient is φ = 6132672.

The previous prime is 21640013. The next prime is 21640039. The reversal of 21640038 is 83004612.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21640039) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3306 + ... + 7362.

It is an arithmetic number, because the mean of its divisors is an integer number (1558272).

Almost surely, 2^21640038 is an apocalyptic number.

21640038 is an abundant number, since it is smaller than the sum of its proper divisors (28224666).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21640038 is a wasteful number, since it uses less digits than its factorization.

21640038 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4196.

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 21640038 is about 4651.8854242124. The cubic root of 21640038 is about 278.6672978194.

The spelling of 21640038 in words is "twenty-one million, six hundred forty thousand, thirty-eight".