81969570 has 40 divisors (see below), whose sum is σ = 220409244. Its totient is φ = 21858336.

The previous prime is 81969557. The next prime is 81969577. The reversal of 81969570 is 7596918.

81969570 is a `hidden beast` number, since 8 + 19 + 69 + 570 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 79869969 + 2099601 = 8937^2 + 1449^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (81969577) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 49789 + ... + 51408.

Almost surely, 2^81969570 is an apocalyptic number.

81969570 is an abundant number, since it is smaller than the sum of its proper divisors (138439674).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81969570 is a wasteful number, since it uses less digits than its factorization.

81969570 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101216 (or 101207 counting only the distinct ones).

The product of its (nonzero) digits is 136080, while the sum is 45.

The square root of 81969570 is about 9053.7047665583. The cubic root of 81969570 is about 434.3944010450.

It can be divided in two parts, 8196 and 9570, that added together give a triangular number (17766 = T₁₈₈).

The spelling of 81969570 in words is "eighty-one million, nine hundred sixty-nine thousand, five hundred seventy".