21981910 has 8 divisors (see below), whose sum is σ = 39567456. Its totient is φ = 8792760.

The previous prime is 21981893. The next prime is 21981923. The reversal of 21981910 is 1918912.

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

It is a congruent number.

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, 1099086 + ... + 1099105.

It is an arithmetic number, because the mean of its divisors is an integer number (4945932).

Almost surely, 2^21981910 is an apocalyptic number.

21981910 is a deficient number, since it is larger than the sum of its proper divisors (17585546).

21981910 is a wasteful number, since it uses less digits than its factorization.

21981910 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2198198.

The product of its (nonzero) digits is 1296, while the sum is 31.

The square root of 21981910 is about 4688.4869627631. The cubic root of 21981910 is about 280.1271106546.

The spelling of 21981910 in words is "twenty-one million, nine hundred eighty-one thousand, nine hundred ten".