1891521972 has 36 divisors (see below), whose sum is σ = 5032998880. Its totient is φ = 597322512.

The previous prime is 1891521971. The next prime is 1891521997. The reversal of 1891521972 is 2791251981.

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1891521971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1382008 + ... + 1383375.

Almost surely, 2^1891521972 is an apocalyptic number.

1891521972 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1891521972 is an abundant number, since it is smaller than the sum of its proper divisors (3141476908).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1891521972 is a wasteful number, since it uses less digits than its factorization.

1891521972 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2765412 (or 2765407 counting only the distinct ones).

The product of its digits is 90720, while the sum is 45.

The square root of 1891521972 is about 43491.6310570206. The cubic root of 1891521972 is about 1236.7173781907.

The spelling of 1891521972 in words is "one billion, eight hundred ninety-one million, five hundred twenty-one thousand, nine hundred seventy-two".