21988965 has 8 divisors (see below), whose sum is σ = 35182368. Its totient is φ = 11727440.

The previous prime is 21988957. The next prime is 21988969. The reversal of 21988965 is 56988912.

It is a happy number.

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

It is not a de Polignac number, because 21988965 - 2³ = 21988957 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21988969) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 732951 + ... + 732980.

It is an arithmetic number, because the mean of its divisors is an integer number (4397796).

Almost surely, 2^21988965 is an apocalyptic number.

It is an amenable number.

21988965 is a deficient number, since it is larger than the sum of its proper divisors (13193403).

21988965 is a wasteful number, since it uses less digits than its factorization.

21988965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1465939.

The product of its digits is 311040, while the sum is 48.

The square root of 21988965 is about 4689.2392773242. The cubic root of 21988965 is about 280.1570759818.

The spelling of 21988965 in words is "twenty-one million, nine hundred eighty-eight thousand, nine hundred sixty-five".