661541269 has 2 divisors, whose sum is σ = 661541270. Its totient is φ = 661541268.

The previous prime is 661541267. The next prime is 661541357. The reversal of 661541269 is 962145166.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 648364369 + 13176900 = 25463^2 + 3630^2 .

It is a cyclic number.

It is not a de Polignac number, because 661541269 - 2¹ = 661541267 is a prime.

It is a super-2 number, since 2×661541269² = 875273701180260722, which contains 22 as substring.

Together with 661541267, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661541263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330770634 + 330770635.

It is an arithmetic number, because the mean of its divisors is an integer number (330770635).

Almost surely, 2^661541269 is an apocalyptic number.

It is an amenable number.

661541269 is a deficient number, since it is larger than the sum of its proper divisors (1).

661541269 is an equidigital number, since it uses as much as digits as its factorization.

661541269 is an evil number, because the sum of its binary digits is even.

The product of its digits is 77760, while the sum is 40.

The square root of 661541269 is about 25720.4445723631. Note that the first 3 decimals coincide. The cubic root of 661541269 is about 871.3359792933.

The spelling of 661541269 in words is "six hundred sixty-one million, five hundred forty-one thousand, two hundred sixty-nine".