19890561 has 32 divisors (see below), whose sum is σ = 30302208. Its totient is φ = 11531520.

The previous prime is 19890523. The next prime is 19890583. The reversal of 19890561 is 16509891.

It is not a de Polignac number, because 19890561 - 2⁹ = 19890049 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (19890061) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 36090 + ... + 36636.

It is an arithmetic number, because the mean of its divisors is an integer number (946944).

Almost surely, 2^19890561 is an apocalyptic number.

It is an amenable number.

19890561 is a deficient number, since it is larger than the sum of its proper divisors (10411647).

19890561 is a wasteful number, since it uses less digits than its factorization.

19890561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 621.

The product of its (nonzero) digits is 19440, while the sum is 39.

The square root of 19890561 is about 4459.8835186583. The cubic root of 19890561 is about 270.9457505912.

The spelling of 19890561 in words is "nineteen million, eight hundred ninety thousand, five hundred sixty-one".