21271988 has 6 divisors (see below), whose sum is σ = 37225986. Its totient is φ = 10635992.

The previous prime is 21271973. The next prime is 21272011. The reversal of 21271988 is 88917212.

It can be written as a sum of positive squares in only one way, i.e., 21270544 + 1444 = 4612^2 + 38^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2658995 + ... + 2659002.

It is an arithmetic number, because the mean of its divisors is an integer number (6204331).

Almost surely, 2^21271988 is an apocalyptic number.

It is an amenable number.

21271988 is a deficient number, since it is larger than the sum of its proper divisors (15953998).

21271988 is a wasteful number, since it uses less digits than its factorization.

21271988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5318001 (or 5317999 counting only the distinct ones).

The product of its digits is 16128, while the sum is 38.

The square root of 21271988 is about 4612.1565454785. The cubic root of 21271988 is about 277.0784140282.

The spelling of 21271988 in words is "twenty-one million, two hundred seventy-one thousand, nine hundred eighty-eight".