1921851389 has 2 divisors, whose sum is σ = 1921851390. Its totient is φ = 1921851388.

The previous prime is 1921851329. The next prime is 1921851433. The reversal of 1921851389 is 9831581291.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1897299364 + 24552025 = 43558^2 + 4955^2 .

It is a cyclic number.

It is not a de Polignac number, because 1921851389 - 2¹² = 1921847293 is a prime.

It is a super-2 number, since 2×1921851389² = 7387025522802458642, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1921851329) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 960925694 + 960925695.

It is an arithmetic number, because the mean of its divisors is an integer number (960925695).

Almost surely, 2^1921851389 is an apocalyptic number.

It is an amenable number.

1921851389 is a deficient number, since it is larger than the sum of its proper divisors (1).

1921851389 is an equidigital number, since it uses as much as digits as its factorization.

1921851389 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 47.

The square root of 1921851389 is about 43838.9255000622. The cubic root of 1921851389 is about 1243.2923668281.

It can be divided in two parts, 19218 and 51389, that added together give a palindrome (70607).

The spelling of 1921851389 in words is "one billion, nine hundred twenty-one million, eight hundred fifty-one thousand, three hundred eighty-nine".