21745851 has 8 divisors (see below), whose sum is σ = 29074944. Its totient is φ = 14457000.

The previous prime is 21745799. The next prime is 21745901. The reversal of 21745851 is 15854712.

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

It is not a de Polignac number, because 21745851 - 2¹³ = 21737659 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21745151) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8775 + ... + 10976.

It is an arithmetic number, because the mean of its divisors is an integer number (3634368).

Almost surely, 2^21745851 is an apocalyptic number.

21745851 is a deficient number, since it is larger than the sum of its proper divisors (7329093).

21745851 is a wasteful number, since it uses less digits than its factorization.

21745851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20121.

The product of its digits is 11200, while the sum is 33.

The square root of 21745851 is about 4663.2446858384. The cubic root of 21745851 is about 279.1207580952.

The spelling of 21745851 in words is "twenty-one million, seven hundred forty-five thousand, eight hundred fifty-one".