1891971421 has 8 divisors (see below), whose sum is σ = 1974700224. Its totient is φ = 1809281760.

The previous prime is 1891971413. The next prime is 1891971437. The reversal of 1891971421 is 1241791981.

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 1891971421 - 2³ = 1891971413 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1891971121) 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, 134305 + ... + 147721.

It is an arithmetic number, because the mean of its divisors is an integer number (246837528).

Almost surely, 2^1891971421 is an apocalyptic number.

It is an amenable number.

1891971421 is a deficient number, since it is larger than the sum of its proper divisors (82728803).

1891971421 is a wasteful number, since it uses less digits than its factorization.

1891971421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19571.

The product of its digits is 36288, while the sum is 43.

The square root of 1891971421 is about 43496.7978246675. The cubic root of 1891971421 is about 1236.8153235451.

The spelling of 1891971421 in words is "one billion, eight hundred ninety-one million, nine hundred seventy-one thousand, four hundred twenty-one".