16221931 has 4 divisors (see below), whose sum is σ = 17696664. Its totient is φ = 14747200.

The previous prime is 16221929. The next prime is 16221971. The reversal of 16221931 is 13912261.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 16221931 - 2¹ = 16221929 is a prime.

It is a super-2 number, since 2×16221931² = 526302090737522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16221896 and 16221905.

It is not an unprimeable number, because it can be changed into a prime (16221901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 737350 + ... + 737371.

It is an arithmetic number, because the mean of its divisors is an integer number (4424166).

Almost surely, 2^16221931 is an apocalyptic number.

16221931 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

16221931 is a deficient number, since it is larger than the sum of its proper divisors (1474733).

16221931 is a wasteful number, since it uses less digits than its factorization.

16221931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1474732.

The product of its digits is 648, while the sum is 25.

The square root of 16221931 is about 4027.6458384520. The cubic root of 16221931 is about 253.1439291031.

It can be divided in two parts, 1622 and 1931, that added together give a palindrome (3553).

The spelling of 16221931 in words is "sixteen million, two hundred twenty-one thousand, nine hundred thirty-one".