1021543981 has 2 divisors, whose sum is σ = 1021543982. Its totient is φ = 1021543980.

The previous prime is 1021543951. The next prime is 1021544033. The reversal of 1021543981 is 1893451201.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 683351881 + 338192100 = 26141^2 + 18390^2 .

It is a cyclic number.

It is not a de Polignac number, because 1021543981 - 2¹¹ = 1021541933 is a prime.

It is a super-2 number, since 2×1021543981² = 2087104210234656722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1021543951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510771990 + 510771991.

It is an arithmetic number, because the mean of its divisors is an integer number (510771991).

Almost surely, 2^1021543981 is an apocalyptic number.

It is an amenable number.

1021543981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1021543981 is an equidigital number, since it uses as much as digits as its factorization.

1021543981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8640, while the sum is 34.

The square root of 1021543981 is about 31961.6016651231. The cubic root of 1021543981 is about 1007.1303640674.

The spelling of 1021543981 in words is "one billion, twenty-one million, five hundred forty-three thousand, nine hundred eighty-one".