1919911561 has 16 divisors (see below), whose sum is σ = 2005217280. Its totient is φ = 1836195840.

The previous prime is 1919911523. The next prime is 1919911583. The reversal of 1919911561 is 1651199191.

It is a cyclic number.

It is not a de Polignac number, because 1919911561 - 2¹³ = 1919903369 is a prime.

It is a super-2 number, since 2×1919911561² = 7372120804122913442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1919911501) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1090600 + ... + 1092358.

It is an arithmetic number, because the mean of its divisors is an integer number (125326080).

Almost surely, 2^1919911561 is an apocalyptic number.

It is an amenable number.

1919911561 is a deficient number, since it is larger than the sum of its proper divisors (85305719).

1919911561 is a wasteful number, since it uses less digits than its factorization.

1919911561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2184.

The product of its digits is 21870, while the sum is 43.

The square root of 1919911561 is about 43816.7954213906. The cubic root of 1919911561 is about 1242.8739187180.

The spelling of 1919911561 in words is "one billion, nine hundred nineteen million, nine hundred eleven thousand, five hundred sixty-one".