16721644 has 12 divisors (see below), whose sum is σ = 30535344. Its totient is φ = 7997264.

The previous prime is 16721641. The next prime is 16721647. The reversal of 16721644 is 44612761.

It is an interprime number because it is at equal distance from previous prime (16721641) and next prime (16721647).

It is a super-2 number, since 2×16721644² = 559226756125472, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (16721641) 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, 90787 + ... + 90970.

It is an arithmetic number, because the mean of its divisors is an integer number (2544612).

Almost surely, 2^16721644 is an apocalyptic number.

It is an amenable number.

16721644 is a deficient number, since it is larger than the sum of its proper divisors (13813700).

16721644 is a wasteful number, since it uses less digits than its factorization.

16721644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 181784 (or 181782 counting only the distinct ones).

The product of its digits is 8064, while the sum is 31.

The square root of 16721644 is about 4089.2106817820. The cubic root of 16721644 is about 255.7170335331.

The spelling of 16721644 in words is "sixteen million, seven hundred twenty-one thousand, six hundred forty-four".