661026213 has 6 divisors (see below), whose sum is σ = 954815654. Its totient is φ = 440684136.

The previous prime is 661026199. The next prime is 661026239. The reversal of 661026213 is 312620166.

661026213 is a `hidden beast` number, since 6 + 610 + 26 + 21 + 3 = 666.

It can be written as a sum of positive squares in only one way, i.e., 408120804 + 252905409 = 20202^2 + 15903^2 .

It is a de Polignac number, because none of the positive numbers 2^k-661026213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661026263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36723670 + ... + 36723687.

Almost surely, 2^661026213 is an apocalyptic number.

It is an amenable number.

661026213 is a deficient number, since it is larger than the sum of its proper divisors (293789441).

661026213 is a wasteful number, since it uses less digits than its factorization.

661026213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73447363 (or 73447360 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 661026213 is about 25710.4300430778. The cubic root of 661026213 is about 871.1097886452.

Adding to 661026213 its reverse (312620166), we get a palindrome (973646379).

It can be divided in two parts, 6610 and 26213, that added together give a palindrome (32823).

The spelling of 661026213 in words is "six hundred sixty-one million, twenty-six thousand, two hundred thirteen".