1231967021 has 2 divisors, whose sum is σ = 1231967022. Its totient is φ = 1231967020.

The previous prime is 1231966969. The next prime is 1231967047. The reversal of 1231967021 is 1207691321.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1222900900 + 9066121 = 34970^2 + 3011^2 .

It is an emirp because it is prime and its reverse (1207691321) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1231967021 - 2²² = 1227772717 is a prime.

It is a super-2 number, since 2×1231967021² = 3035485481663228882, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1231964021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615983510 + 615983511.

It is an arithmetic number, because the mean of its divisors is an integer number (615983511).

Almost surely, 2^1231967021 is an apocalyptic number.

It is an amenable number.

1231967021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231967021 is an equidigital number, since it uses as much as digits as its factorization.

1231967021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 32.

The square root of 1231967021 is about 35099.3877581932. The cubic root of 1231967021 is about 1072.0121165766.

The spelling of 1231967021 in words is "one billion, two hundred thirty-one million, nine hundred sixty-seven thousand, twenty-one".