81745970 has 8 divisors (see below), whose sum is σ = 147142764. Its totient is φ = 32698384.

The previous prime is 81745957. The next prime is 81745973. The reversal of 81745970 is 7954718.

It can be written as a sum of positive squares in 2 ways, for example, as 72607441 + 9138529 = 8521^2 + 3023^2 .

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

It is a super-2 number, since 2×81745970² = 13364807222481800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81745973) 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, 4087289 + ... + 4087308.

Almost surely, 2^81745970 is an apocalyptic number.

81745970 is a deficient number, since it is larger than the sum of its proper divisors (65396794).

81745970 is a wasteful number, since it uses less digits than its factorization.

81745970 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8174604.

The product of its (nonzero) digits is 70560, while the sum is 41.

The square root of 81745970 is about 9041.3477977567. The cubic root of 81745970 is about 433.9990549789. Note that the first 3 decimals are identical.

The spelling of 81745970 in words is "eighty-one million, seven hundred forty-five thousand, nine hundred seventy".