21751390 has 32 divisors (see below), whose sum is σ = 41472000. Its totient is φ = 8191008.

The previous prime is 21751369. The next prime is 21751391. The reversal of 21751390 is 9315712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21751391) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45171 + ... + 45649.

It is an arithmetic number, because the mean of its divisors is an integer number (1296000).

Almost surely, 2^21751390 is an apocalyptic number.

21751390 is a deficient number, since it is larger than the sum of its proper divisors (19720610).

21751390 is a wasteful number, since it uses less digits than its factorization.

21751390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 744.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 21751390 is about 4663.8385478059. The cubic root of 21751390 is about 279.1444548551.

The spelling of 21751390 in words is "twenty-one million, seven hundred fifty-one thousand, three hundred ninety".