70320821 has 4 divisors (see below), whose sum is σ = 73378272. Its totient is φ = 67263372.

The previous prime is 70320787. The next prime is 70320847. The reversal of 70320821 is 12802307.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12802307 = 7 ⋅1828901.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-70320821 is a prime.

It is a super-2 number, since 2×70320821² = 9890035732228082, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (23), and also a Moran number because the ratio is a prime number: 3057427 = 70320821 / (7 + 0 + 3 + 2 + 0 + 8 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (70320221) 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, 1528691 + ... + 1528736.

It is an arithmetic number, because the mean of its divisors is an integer number (18344568).

Almost surely, 2^70320821 is an apocalyptic number.

It is an amenable number.

70320821 is a deficient number, since it is larger than the sum of its proper divisors (3057451).

70320821 is a wasteful number, since it uses less digits than its factorization.

70320821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3057450.

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 70320821 is about 8385.7510695226. The cubic root of 70320821 is about 412.7571871506.

The spelling of 70320821 in words is "seventy million, three hundred twenty thousand, eight hundred twenty-one".