16621540 has 24 divisors (see below), whose sum is σ = 37590840. Its totient is φ = 6137088.

The previous prime is 16621513. The next prime is 16621541. The reversal of 16621540 is 4512661.

It can be written as a sum of positive squares in 4 ways, for example, as 186624 + 16434916 = 432^2 + 4054^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16621541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31705 + ... + 32224.

It is an arithmetic number, because the mean of its divisors is an integer number (1566285).

Almost surely, 2^16621540 is an apocalyptic number.

16621540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

16621540 is an abundant number, since it is smaller than the sum of its proper divisors (20969300).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

16621540 is a wasteful number, since it uses less digits than its factorization.

16621540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63951 (or 63949 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 16621540 is about 4076.9522930738. The cubic root of 16621540 is about 255.2057291455.

It can be divided in two parts, 16621 and 540, that added together give a square (17161 = 131²).

The spelling of 16621540 in words is "sixteen million, six hundred twenty-one thousand, five hundred forty".