213667991 has 2 divisors, whose sum is σ = 213667992. Its totient is φ = 213667990.

The previous prime is 213667967. The next prime is 213667997. The reversal of 213667991 is 199766312.

213667991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-213667991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (213667997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106833995 + 106833996.

It is an arithmetic number, because the mean of its divisors is an integer number (106833996).

Almost surely, 2^213667991 is an apocalyptic number.

213667991 is a deficient number, since it is larger than the sum of its proper divisors (1).

213667991 is an equidigital number, since it uses as much as digits as its factorization.

213667991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 122472, while the sum is 44.

The square root of 213667991 is about 14617.3865995259. The cubic root of 213667991 is about 597.8329147331.

The spelling of 213667991 in words is "two hundred thirteen million, six hundred sixty-seven thousand, nine hundred ninety-one".