1021212091 has 2 divisors, whose sum is σ = 1021212092. Its totient is φ = 1021212090.

The previous prime is 1021212079. The next prime is 1021212107. The reversal of 1021212091 is 1902121201.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (1902121201) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1021212091 is a prime.

It is not a weakly prime, because it can be changed into another prime (1021212791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510606045 + 510606046.

It is an arithmetic number, because the mean of its divisors is an integer number (510606046).

Almost surely, 2^1021212091 is an apocalyptic number.

1021212091 is a deficient number, since it is larger than the sum of its proper divisors (1).

1021212091 is an equidigital number, since it uses as much as digits as its factorization.

1021212091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 19.

The square root of 1021212091 is about 31956.4092319522. The cubic root of 1021212091 is about 1007.0212832028.

Adding to 1021212091 its reverse (1902121201), we get a palindrome (2923333292).

The spelling of 1021212091 in words is "one billion, twenty-one million, two hundred twelve thousand, ninety-one".