78724502921 has 16 divisors (see below), whose sum is σ = 85106355264. Its totient is φ = 72553012224.

The previous prime is 78724502863. The next prime is 78724502933. The reversal of 78724502921 is 12920542787.

It is a cyclic number.

It is not a de Polignac number, because 78724502921 - 2²² = 78720308617 is a prime.

It is not an unprimeable number, because it can be changed into a prime (78724502221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 87431 + ... + 406316.

It is an arithmetic number, because the mean of its divisors is an integer number (5319147204).

Almost surely, 2^78724502921 is an apocalyptic number.

It is an amenable number.

78724502921 is a deficient number, since it is larger than the sum of its proper divisors (6381852343).

78724502921 is a wasteful number, since it uses less digits than its factorization.

78724502921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 493960.

The product of its (nonzero) digits is 564480, while the sum is 47.

The spelling of 78724502921 in words is "seventy-eight billion, seven hundred twenty-four million, five hundred two thousand, nine hundred twenty-one".