21712938 has 48 divisors (see below), whose sum is σ = 48580896. Its totient is φ = 6431040.

The previous prime is 21712931. The next prime is 21712939. The reversal of 21712938 is 83921712.

Its product of digits (6048) is a multiple of the sum of its prime divisors (378).

It is a junction number, because it is equal to n+sod(n) for n = 21712899 and 21712908.

It is not an unprimeable number, because it can be changed into a prime (21712931) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 65433 + ... + 65763.

It is an arithmetic number, because the mean of its divisors is an integer number (1012102).

Almost surely, 2^21712938 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21712938, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24290448).

21712938 is an abundant number, since it is smaller than the sum of its proper divisors (26867958).

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

21712938 is a wasteful number, since it uses less digits than its factorization.

21712938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407 (or 378 counting only the distinct ones).

The product of its digits is 6048, while the sum is 33.

The square root of 21712938 is about 4659.7143689286. The cubic root of 21712938 is about 278.9798677679.

The spelling of 21712938 in words is "twenty-one million, seven hundred twelve thousand, nine hundred thirty-eight".