1378405621 has 2 divisors, whose sum is σ = 1378405622. Its totient is φ = 1378405620.

The previous prime is 1378405591. The next prime is 1378405627. The reversal of 1378405621 is 1265048731.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1266363396 + 112042225 = 35586^2 + 10585^2 .

It is a cyclic number.

It is not a de Polignac number, because 1378405621 - 2²³ = 1370017013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1378405627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 689202810 + 689202811.

It is an arithmetic number, because the mean of its divisors is an integer number (689202811).

Almost surely, 2^1378405621 is an apocalyptic number.

It is an amenable number.

1378405621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1378405621 is an equidigital number, since it uses as much as digits as its factorization.

1378405621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40320, while the sum is 37.

The square root of 1378405621 is about 37126.8854201373. The cubic root of 1378405621 is about 1112.9073530095.

The spelling of 1378405621 in words is "one billion, three hundred seventy-eight million, four hundred five thousand, six hundred twenty-one".