78253621 has 2 divisors, whose sum is σ = 78253622. Its totient is φ = 78253620.

The previous prime is 78253603. The next prime is 78253627. The reversal of 78253621 is 12635287.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69072721 + 9180900 = 8311^2 + 3030^2 .

It is a cyclic number.

It is not a de Polignac number, because 78253621 - 2⁵ = 78253589 is a prime.

It is a super-2 number, since 2×78253621² = 12247258399223282, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78253627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39126810 + 39126811.

It is an arithmetic number, because the mean of its divisors is an integer number (39126811).

Almost surely, 2^78253621 is an apocalyptic number.

It is an amenable number.

78253621 is a deficient number, since it is larger than the sum of its proper divisors (1).

78253621 is an equidigital number, since it uses as much as digits as its factorization.

78253621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20160, while the sum is 34.

The square root of 78253621 is about 8846.1076751303. The cubic root of 78253621 is about 427.7284594455.

The spelling of 78253621 in words is "seventy-eight million, two hundred fifty-three thousand, six hundred twenty-one".