20749221 has 12 divisors (see below), whose sum is σ = 30201600. Its totient is φ = 13726440.

The previous prime is 20749213. The next prime is 20749229. The reversal of 20749221 is 12294702.

It is an interprime number because it is at equal distance from previous prime (20749213) and next prime (20749229).

It is not a de Polignac number, because 20749221 - 2³ = 20749213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20749229) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7621 + ... + 9978.

It is an arithmetic number, because the mean of its divisors is an integer number (2516800).

Almost surely, 2^20749221 is an apocalyptic number.

It is an amenable number.

20749221 is a deficient number, since it is larger than the sum of its proper divisors (9452379).

20749221 is a wasteful number, since it uses less digits than its factorization.

20749221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17736 (or 17733 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 20749221 is about 4555.1312824111. The cubic root of 20749221 is about 274.7897941837.

The spelling of 20749221 in words is "twenty million, seven hundred forty-nine thousand, two hundred twenty-one".