15940221 has 16 divisors (see below), whose sum is σ = 24407040. Its totient is φ = 9151920.

The previous prime is 15940213. The next prime is 15940241. The reversal of 15940221 is 12204951.

It is not a de Polignac number, because 15940221 - 2³ = 15940213 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 15940191 and 15940200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15940201) 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, 12085 + ... + 13338.

It is an arithmetic number, because the mean of its divisors is an integer number (1525440).

Almost surely, 2^15940221 is an apocalyptic number.

15940221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

15940221 is a deficient number, since it is larger than the sum of its proper divisors (8466819).

15940221 is a wasteful number, since it uses less digits than its factorization.

15940221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25456.

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 15940221 is about 3992.5206323825. The cubic root of 15940221 is about 251.6699982503.

It can be divided in two parts, 15940 and 221, that added together give a palindrome (16161).

The spelling of 15940221 in words is "fifteen million, nine hundred forty thousand, two hundred twenty-one".