213788781 has 8 divisors (see below), whose sum is σ = 316724160. Its totient is φ = 142525836.

The previous prime is 213788761. The next prime is 213788789. The reversal of 213788781 is 187887312.

It is not a de Polignac number, because 213788781 - 2¹⁸ = 213526637 is a prime.

It is a super-2 number, since 2×213788781² = 91411285762931922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (213788789) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3959025 + ... + 3959078.

It is an arithmetic number, because the mean of its divisors is an integer number (39590520).

Almost surely, 2^213788781 is an apocalyptic number.

It is an amenable number.

213788781 is a deficient number, since it is larger than the sum of its proper divisors (102935379).

213788781 is an equidigital number, since it uses as much as digits as its factorization.

213788781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7918112 (or 7918106 counting only the distinct ones).

The product of its digits is 150528, while the sum is 45.

The square root of 213788781 is about 14621.5177392773. The cubic root of 213788781 is about 597.9455484102.

The spelling of 213788781 in words is "two hundred thirteen million, seven hundred eighty-eight thousand, seven hundred eighty-one".