21881506 has 8 divisors (see below), whose sum is σ = 32889024. Its totient is φ = 10918500.

The previous prime is 21881491. The next prime is 21881513. The reversal of 21881506 is 60518812.

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9870 + ... + 11881.

It is an arithmetic number, because the mean of its divisors is an integer number (4111128).

Almost surely, 2^21881506 is an apocalyptic number.

21881506 is a deficient number, since it is larger than the sum of its proper divisors (11007518).

21881506 is a wasteful number, since it uses less digits than its factorization.

21881506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22256.

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 21881506 is about 4677.7672024161. The cubic root of 21881506 is about 279.6999592111.

The spelling of 21881506 in words is "twenty-one million, eight hundred eighty-one thousand, five hundred six".