78154352721 has 9 divisors (see below), whose sum is σ = 112890832041. Its totient is φ = 52102342692.

The previous prime is 78154352699. The next prime is 78154352723. The reversal of 78154352721 is 12725345187.

The square root of 78154352721 is 279561.

It is a perfect power (a square), and thus also a powerful number.

78154352721 is a `hidden beast` number, since 7 + 81 + 5 + 43 + 527 + 2 + 1 = 666.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 78154352721 - 2⁷ = 78154352593 is a prime.

It is a super-2 number, since 2×78154352721² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78154352723) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 792090 + ... + 885276.

Almost surely, 2^78154352721 is an apocalyptic number.

78154352721 is the 279561-st square number.

78154352721 is the 139781-st centered octagonal number.

It is an amenable number.

78154352721 is a deficient number, since it is larger than the sum of its proper divisors (34736479320).

78154352721 is an frugal number, since it uses more digits than its factorization.

78154352721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186380 (or 93190 counting only the distinct ones).

The product of its digits is 470400, while the sum is 45.

The spelling of 78154352721 in words is "seventy-eight billion, one hundred fifty-four million, three hundred fifty-two thousand, seven hundred twenty-one".