139761781 has 2 divisors, whose sum is σ = 139761782. Its totient is φ = 139761780.

The previous prime is 139761749. The next prime is 139761793. The reversal of 139761781 is 187167931.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 123432100 + 16329681 = 11110^2 + 4041^2 .

It is a cyclic number.

It is not a de Polignac number, because 139761781 - 2⁵ = 139761749 is a prime.

It is a super-2 number, since 2×139761781² = 39066710856583922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (139771781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69880890 + 69880891.

It is an arithmetic number, because the mean of its divisors is an integer number (69880891).

Almost surely, 2^139761781 is an apocalyptic number.

It is an amenable number.

139761781 is a deficient number, since it is larger than the sum of its proper divisors (1).

139761781 is an equidigital number, since it uses as much as digits as its factorization.

139761781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 63504, while the sum is 43.

The square root of 139761781 is about 11822.0886902442. The cubic root of 139761781 is about 518.9547308994.

The spelling of 139761781 in words is "one hundred thirty-nine million, seven hundred sixty-one thousand, seven hundred eighty-one".