71149781 has 2 divisors, whose sum is σ = 71149782. Its totient is φ = 71149780.

The previous prime is 71149769. The next prime is 71149807. The reversal of 71149781 is 18794117.

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., 69872881 + 1276900 = 8359^2 + 1130^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71149781 is a prime.

It is a super-2 number, since 2×71149781² = 10124582672695922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71149721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35574890 + 35574891.

It is an arithmetic number, because the mean of its divisors is an integer number (35574891).

Almost surely, 2^71149781 is an apocalyptic number.

It is an amenable number.

71149781 is a deficient number, since it is larger than the sum of its proper divisors (1).

71149781 is an equidigital number, since it uses as much as digits as its factorization.

71149781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14112, while the sum is 38.

The square root of 71149781 is about 8435.0329578491. The cubic root of 71149781 is about 414.3727515619.

The spelling of 71149781 in words is "seventy-one million, one hundred forty-nine thousand, seven hundred eighty-one".