1921895561 has 16 divisors (see below), whose sum is σ = 2004238848. Its totient is φ = 1840924800.

The previous prime is 1921895537. The next prime is 1921895567. The reversal of 1921895561 is 1655981291.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1921895561 - 2¹⁰ = 1921894537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1921895567) 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, 1610381 + ... + 1611573.

It is an arithmetic number, because the mean of its divisors is an integer number (125264928).

Almost surely, 2^1921895561 is an apocalyptic number.

It is an amenable number.

1921895561 is a deficient number, since it is larger than the sum of its proper divisors (82343287).

1921895561 is a wasteful number, since it uses less digits than its factorization.

1921895561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1712.

The product of its digits is 194400, while the sum is 47.

The square root of 1921895561 is about 43839.4292960116. The cubic root of 1921895561 is about 1243.3018920685.

The spelling of 1921895561 in words is "one billion, nine hundred twenty-one million, eight hundred ninety-five thousand, five hundred sixty-one".