21938890 has 8 divisors (see below), whose sum is σ = 39490020. Its totient is φ = 8775552.

The previous prime is 21938881. The next prime is 21938899. The reversal of 21938890 is 9883912.

It is an interprime number because it is at equal distance from previous prime (21938881) and next prime (21938899).

It can be written as a sum of positive squares in 2 ways, for example, as 21335161 + 603729 = 4619^2 + 777^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21938899) 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, 1096935 + ... + 1096954.

Almost surely, 2^21938890 is an apocalyptic number.

21938890 is a deficient number, since it is larger than the sum of its proper divisors (17551130).

21938890 is a wasteful number, since it uses less digits than its factorization.

21938890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2193896.

The product of its (nonzero) digits is 31104, while the sum is 40.

The square root of 21938890 is about 4683.8968818709. The cubic root of 21938890 is about 279.9442491042.

The spelling of 21938890 in words is "twenty-one million, nine hundred thirty-eight thousand, eight hundred ninety".