21791288 has 8 divisors (see below), whose sum is σ = 40858680. Its totient is φ = 10895640.

The previous prime is 21791279. The next prime is 21791291. The reversal of 21791288 is 88219712.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1361948 + ... + 1361963.

It is an arithmetic number, because the mean of its divisors is an integer number (5107335).

Almost surely, 2^21791288 is an apocalyptic number.

It is an amenable number.

21791288 is a deficient number, since it is larger than the sum of its proper divisors (19067392).

21791288 is a wasteful number, since it uses less digits than its factorization.

21791288 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2723917 (or 2723913 counting only the distinct ones).

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

The square root of 21791288 is about 4668.1139660467. The cubic root of 21791288 is about 279.3150263722.

The spelling of 21791288 in words is "twenty-one million, seven hundred ninety-one thousand, two hundred eighty-eight".