78297421 has 2 divisors, whose sum is σ = 78297422. Its totient is φ = 78297420.

The previous prime is 78297409. The next prime is 78297431. The reversal of 78297421 is 12479287.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69806025 + 8491396 = 8355^2 + 2914^2 .

It is a cyclic number.

It is not a de Polignac number, because 78297421 - 2⁵ = 78297389 is a prime.

It is a super-2 number, since 2×78297421² = 12260972270502482, which contains 22 as substring.

It is equal to p_4575883 and since 78297421 and 4575883 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78297431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39148710 + 39148711.

It is an arithmetic number, because the mean of its divisors is an integer number (39148711).

Almost surely, 2^78297421 is an apocalyptic number.

It is an amenable number.

78297421 is a deficient number, since it is larger than the sum of its proper divisors (1).

78297421 is an equidigital number, since it uses as much as digits as its factorization.

78297421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 56448, while the sum is 40.

The square root of 78297421 is about 8848.5829939036. The cubic root of 78297421 is about 427.8082470729.

The spelling of 78297421 in words is "seventy-eight million, two hundred ninety-seven thousand, four hundred twenty-one".