1025891989 has 2 divisors, whose sum is σ = 1025891990. Its totient is φ = 1025891988.

The previous prime is 1025891987. The next prime is 1025892001. The reversal of 1025891989 is 9891985201.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 844774225 + 181117764 = 29065^2 + 13458^2 .

It is a cyclic number.

It is not a de Polignac number, because 1025891989 - 2¹ = 1025891987 is a prime.

It is a super-4 number, since 4×1025891989⁴ (a number of 37 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

Together with 1025891987, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1025891987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 512945994 + 512945995.

It is an arithmetic number, because the mean of its divisors is an integer number (512945995).

Almost surely, 2^1025891989 is an apocalyptic number.

It is an amenable number.

1025891989 is a deficient number, since it is larger than the sum of its proper divisors (1).

1025891989 is an equidigital number, since it uses as much as digits as its factorization.

1025891989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 466560, while the sum is 52.

The square root of 1025891989 is about 32029.5486855497. The cubic root of 1025891989 is about 1008.5572279784.

The spelling of 1025891989 in words is "one billion, twenty-five million, eight hundred ninety-one thousand, nine hundred eighty-nine".