661913531 has 2 divisors, whose sum is σ = 661913532. Its totient is φ = 661913530.

The previous prime is 661913521. The next prime is 661913537. The reversal of 661913531 is 135319166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661913531 - 2⁶ = 661913467 is a prime.

It is a super-2 number, since 2×661913531² = 876259045041775922, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 661913491 and 661913500.

It is not a weakly prime, because it can be changed into another prime (661913537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330956765 + 330956766.

It is an arithmetic number, because the mean of its divisors is an integer number (330956766).

Almost surely, 2^661913531 is an apocalyptic number.

661913531 is a deficient number, since it is larger than the sum of its proper divisors (1).

661913531 is an equidigital number, since it uses as much as digits as its factorization.

661913531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14580, while the sum is 35.

The square root of 661913531 is about 25727.6802491014. The cubic root of 661913531 is about 871.4993878194.

It can be divided in two parts, 6619135 and 31, that added together give a palindrome (6619166).

The spelling of 661913531 in words is "six hundred sixty-one million, nine hundred thirteen thousand, five hundred thirty-one".