16621405 has 8 divisors (see below), whose sum is σ = 19971000. Its totient is φ = 13280256.

The previous prime is 16621391. The next prime is 16621417. The reversal of 16621405 is 50412661.

It can be written as a sum of positive squares in 4 ways, for example, as 7513081 + 9108324 = 2741^2 + 3018^2 .

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 16621405 - 2⁹ = 16620893 is a prime.

It is a super-2 number, since 2×16621405² = 552542208348050, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 16621405.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3661 + ... + 6829.

It is an arithmetic number, because the mean of its divisors is an integer number (2496375).

Almost surely, 2^16621405 is an apocalyptic number.

It is an amenable number.

16621405 is a deficient number, since it is larger than the sum of its proper divisors (3349595).

16621405 is a wasteful number, since it uses less digits than its factorization.

16621405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4223.

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

The square root of 16621405 is about 4076.9357365551. The cubic root of 16621405 is about 255.2050382174.

The spelling of 16621405 in words is "sixteen million, six hundred twenty-one thousand, four hundred five".