16920561 has 8 divisors (see below), whose sum is σ = 25783744. Its totient is φ = 9668880.

The previous prime is 16920539. The next prime is 16920569. The reversal of 16920561 is 16502961.

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

It is not a de Polignac number, because 16920561 - 2⁵ = 16920529 is a prime.

It is a super-3 number, since 3×16920561³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (16920569) 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, 402850 + ... + 402891.

It is an arithmetic number, because the mean of its divisors is an integer number (3222968).

Almost surely, 2^16920561 is an apocalyptic number.

It is an amenable number.

16920561 is a deficient number, since it is larger than the sum of its proper divisors (8863183).

16920561 is an equidigital number, since it uses as much as digits as its factorization.

16920561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 805751.

The product of its (nonzero) digits is 3240, while the sum is 30.

The square root of 16920561 is about 4113.4609515589. The cubic root of 16920561 is about 256.7270237171.

The spelling of 16920561 in words is "sixteen million, nine hundred twenty thousand, five hundred sixty-one".