78272921 has 2 divisors, whose sum is σ = 78272922. Its totient is φ = 78272920.

The previous prime is 78272903. The next prime is 78272927. The reversal of 78272921 is 12927287.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78074896 + 198025 = 8836^2 + 445^2 .

It is a cyclic number.

It is not a de Polignac number, because 78272921 - 2¹⁴ = 78256537 is a prime.

It is a super-2 number, since 2×78272921² = 12253300323744482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78272927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39136460 + 39136461.

It is an arithmetic number, because the mean of its divisors is an integer number (39136461).

Almost surely, 2^78272921 is an apocalyptic number.

It is an amenable number.

78272921 is a deficient number, since it is larger than the sum of its proper divisors (1).

78272921 is an equidigital number, since it uses as much as digits as its factorization.

78272921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 28224, while the sum is 38.

The square root of 78272921 is about 8847.1984831358. The cubic root of 78272921 is about 427.7636206755.

The spelling of 78272921 in words is "seventy-eight million, two hundred seventy-two thousand, nine hundred twenty-one".