78687050021 has 4 divisors (see below), whose sum is σ = 78844740000. Its totient is φ = 78529360044.

The previous prime is 78687049993. The next prime is 78687050059. The reversal of 78687050021 is 12005078687.

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: 12005078687 = 7 ⋅1715011241.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78687050021 is a prime.

It is a super-2 number, since 2×78687050021² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78687050621) 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, 78844241 + ... + 78845238.

It is an arithmetic number, because the mean of its divisors is an integer number (19711185000).

Almost surely, 2^78687050021 is an apocalyptic number.

It is an amenable number.

78687050021 is a deficient number, since it is larger than the sum of its proper divisors (157689979).

78687050021 is a wasteful number, since it uses less digits than its factorization.

78687050021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157689978.

The product of its (nonzero) digits is 188160, while the sum is 44.

The spelling of 78687050021 in words is "seventy-eight billion, six hundred eighty-seven million, fifty thousand, twenty-one".