16505621 has 4 divisors (see below), whose sum is σ = 18006144. Its totient is φ = 15005100.

The previous prime is 16505603. The next prime is 16505627. The reversal of 16505621 is 12650561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 16505621 - 2⁶ = 16505557 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16505627) 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, 750245 + ... + 750266.

It is an arithmetic number, because the mean of its divisors is an integer number (4501536).

Almost surely, 2^16505621 is an apocalyptic number.

16505621 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

16505621 is a deficient number, since it is larger than the sum of its proper divisors (1500523).

16505621 is a wasteful number, since it uses less digits than its factorization.

16505621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1500522.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 16505621 is about 4062.7110406722. The cubic root of 16505621 is about 254.6110744204.

The spelling of 16505621 in words is "sixteen million, five hundred five thousand, six hundred twenty-one".