• 70 can be written using four 4's:
It is a happy number.
70 is nontrivially palindromic in base 9 and base 13.
70 is an esthetic number in base 3 and base 4, because in such bases its adjacent digits differ by 1.
It is a sphenic number, since it is the product of 3 distinct primes.
70 is an admirable number.
It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.
70 is an idoneal number.
It is a magnanimous number.
It is an alternating number because its digits alternate between odd and even.
70 is an undulating number in base 3.
70 is a nontrivial repdigit in base 9 and base 13.
It is a plaindrome in base 9, base 12, base 13, base 15 and base 16.
It is a nialpdrome in base 9, base 10, base 11, base 13 and base 14.
It is a zygodrome in base 9 and base 13.
It is a congruent number.
70 is the 7-th pentagonal number.
70 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.
70 is a wasteful number, since it uses less digits than its factorization.
70 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 14.
The square root of 70 is about 8.3666002653. The cubic root of 70 is about 4.1212852998.