212901781 has 2 divisors, whose sum is σ = 212901782. Its totient is φ = 212901780.

The previous prime is 212901763. The next prime is 212901791. The reversal of 212901781 is 187109212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 181440900 + 31460881 = 13470^2 + 5609^2 .

It is a cyclic number.

It is not a de Polignac number, because 212901781 - 2¹¹ = 212899733 is a prime.

It is a super-2 number, since 2×212901781² = 90654336705943922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (212901701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106450890 + 106450891.

It is an arithmetic number, because the mean of its divisors is an integer number (106450891).

Almost surely, 2^212901781 is an apocalyptic number.

It is an amenable number.

212901781 is a deficient number, since it is larger than the sum of its proper divisors (1).

212901781 is an equidigital number, since it uses as much as digits as its factorization.

212901781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 31.

The square root of 212901781 is about 14591.1542038319. The cubic root of 212901781 is about 597.1174524132.

The spelling of 212901781 in words is "two hundred twelve million, nine hundred one thousand, seven hundred eighty-one".