21881386 has 8 divisors (see below), whose sum is σ = 33012324. Its totient is φ = 10877280.

The previous prime is 21881383. The next prime is 21881459. The reversal of 21881386 is 68318812.

It can be written as a sum of positive squares in 2 ways, for example, as 21483225 + 398161 = 4635^2 + 631^2 .

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 (21881383) 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, 31275 + ... + 31966.

Almost surely, 2^21881386 is an apocalyptic number.

21881386 is a deficient number, since it is larger than the sum of its proper divisors (11130938).

21881386 is a wasteful number, since it uses less digits than its factorization.

21881386 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63416.

The product of its digits is 18432, while the sum is 37.

The square root of 21881386 is about 4677.7543757662. The cubic root of 21881386 is about 279.6994479109.

The spelling of 21881386 in words is "twenty-one million, eight hundred eighty-one thousand, three hundred eighty-six".