78070821 has 4 divisors (see below), whose sum is σ = 104094432. Its totient is φ = 52047212.

The previous prime is 78070801. The next prime is 78070823. The reversal of 78070821 is 12807087.

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: 12807087 = 3 ⋅4269029.

It is a cyclic number.

It is not a de Polignac number, because 78070821 - 2⁷ = 78070693 is a prime.

It is a super-2 number, since 2×78070821² = 12190106183228082, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78070823) 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 3 ways as a sum of consecutive naturals, for example, 13011801 + ... + 13011806.

It is an arithmetic number, because the mean of its divisors is an integer number (26023608).

Almost surely, 2^78070821 is an apocalyptic number.

It is an amenable number.

78070821 is a deficient number, since it is larger than the sum of its proper divisors (26023611).

78070821 is a wasteful number, since it uses less digits than its factorization.

78070821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26023610.

The product of its (nonzero) digits is 6272, while the sum is 33.

The square root of 78070821 is about 8835.7694062260. The cubic root of 78070821 is about 427.3951427106.

The spelling of 78070821 in words is "seventy-eight million, seventy thousand, eight hundred twenty-one".