16401821 has 8 divisors (see below), whose sum is σ = 17927424. Its totient is φ = 14938560.

The previous prime is 16401811. The next prime is 16401839. The reversal of 16401821 is 12810461.

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

It is a cyclic number.

It is not a de Polignac number, because 16401821 - 2⁶ = 16401757 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16401811) 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, 15035 + ... + 16088.

It is an arithmetic number, because the mean of its divisors is an integer number (2240928).

Almost surely, 2^16401821 is an apocalyptic number.

It is an amenable number.

16401821 is a deficient number, since it is larger than the sum of its proper divisors (1525603).

16401821 is a wasteful number, since it uses less digits than its factorization.

16401821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31171.

The product of its (nonzero) digits is 384, while the sum is 23.

The square root of 16401821 is about 4049.9161719720. The cubic root of 16401821 is about 254.0762217771.

The spelling of 16401821 in words is "sixteen million, four hundred one thousand, eight hundred twenty-one".