1010021981 has 2 divisors, whose sum is σ = 1010021982. Its totient is φ = 1010021980.

The previous prime is 1010021953. The next prime is 1010021989. The reversal of 1010021981 is 1891200101.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 651525625 + 358496356 = 25525^2 + 18934^2 .

It is a cyclic number.

It is not a de Polignac number, because 1010021981 - 2¹⁴ = 1010005597 is a prime.

It is a super-2 number, since 2×1010021981² = 2040288804206328722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1010021989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 505010990 + 505010991.

It is an arithmetic number, because the mean of its divisors is an integer number (505010991).

Almost surely, 2^1010021981 is an apocalyptic number.

It is an amenable number.

1010021981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1010021981 is an equidigital number, since it uses as much as digits as its factorization.

1010021981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 23.

The square root of 1010021981 is about 31780.8429875609. The cubic root of 1010021981 is about 1003.3295620461.

The spelling of 1010021981 in words is "one billion, ten million, twenty-one thousand, nine hundred eighty-one".