21887906 has 8 divisors (see below), whose sum is σ = 32856300. Its totient is φ = 10935808.

The previous prime is 21887897. The next prime is 21887909. The reversal of 21887906 is 60978812.

It can be written as a sum of positive squares in 2 ways, for example, as 14891881 + 6996025 = 3859^2 + 2645^2 .

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 (21887909) 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, 170 + ... + 6618.

Almost surely, 2^21887906 is an apocalyptic number.

21887906 is a deficient number, since it is larger than the sum of its proper divisors (10968394).

21887906 is a wasteful number, since it uses less digits than its factorization.

21887906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8148.

The product of its (nonzero) digits is 48384, while the sum is 41.

The square root of 21887906 is about 4678.4512394595. The cubic root of 21887906 is about 279.7272258481.

The spelling of 21887906 in words is "twenty-one million, eight hundred eighty-seven thousand, nine hundred six".