78756021 has 24 divisors (see below), whose sum is σ = 116454624. Its totient is φ = 51274080.

The previous prime is 78755987. The next prime is 78756059. The reversal of 78756021 is 12065787.

78756021 is a `hidden beast` number, since 78 + 7 + 560 + 21 = 666.

It is not a de Polignac number, because 78756021 - 2¹⁴ = 78739637 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78754021) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 78495 + ... + 79491.

It is an arithmetic number, because the mean of its divisors is an integer number (4852276).

Almost surely, 2^78756021 is an apocalyptic number.

It is an amenable number.

78756021 is a deficient number, since it is larger than the sum of its proper divisors (37698603).

78756021 is a wasteful number, since it uses less digits than its factorization.

78756021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1201 (or 1198 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 36.

The square root of 78756021 is about 8874.4589130831. The cubic root of 78756021 is about 428.6418678031.

The spelling of 78756021 in words is "seventy-eight million, seven hundred fifty-six thousand, twenty-one".