81261970 has 8 divisors (see below), whose sum is σ = 146271564. Its totient is φ = 32504784.

The previous prime is 81261913. The next prime is 81261977. The reversal of 81261970 is 7916218.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 70744921 + 10517049 = 8411^2 + 3243^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (81261977) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4063089 + ... + 4063108.

Almost surely, 2^81261970 is an apocalyptic number.

81261970 is a deficient number, since it is larger than the sum of its proper divisors (65009594).

81261970 is a wasteful number, since it uses less digits than its factorization.

81261970 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8126204.

The product of its (nonzero) digits is 6048, while the sum is 34.

The square root of 81261970 is about 9014.5421403419. The cubic root of 81261970 is about 433.1408211278.

The spelling of 81261970 in words is "eighty-one million, two hundred sixty-one thousand, nine hundred seventy".