81970649 has 4 divisors (see below), whose sum is σ = 81995520. Its totient is φ = 81945780.

The previous prime is 81970639. The next prime is 81970673. The reversal of 81970649 is 94607918.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81970649 - 2⁸ = 81970393 is a prime.

It is a super-3 number, since 3×81970649³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81970639) 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, 6569 + ... + 14390.

It is an arithmetic number, because the mean of its divisors is an integer number (20498880).

Almost surely, 2^81970649 is an apocalyptic number.

It is an amenable number.

81970649 is a deficient number, since it is larger than the sum of its proper divisors (24871).

81970649 is a wasteful number, since it uses less digits than its factorization.

81970649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24870.

The product of its (nonzero) digits is 108864, while the sum is 44.

The square root of 81970649 is about 9053.7643552282. The cubic root of 81970649 is about 434.3963070755.

The spelling of 81970649 in words is "eighty-one million, nine hundred seventy thousand, six hundred forty-nine".