1978462391 has 2 divisors, whose sum is σ = 1978462392. Its totient is φ = 1978462390.

The previous prime is 1978462319. The next prime is 1978462411. The reversal of 1978462391 is 1932648791.

Together with previous prime (1978462319) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1978462391 - 2¹⁸ = 1978200247 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1978452391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 989231195 + 989231196.

It is an arithmetic number, because the mean of its divisors is an integer number (989231196).

Almost surely, 2^1978462391 is an apocalyptic number.

1978462391 is a deficient number, since it is larger than the sum of its proper divisors (1).

1978462391 is an equidigital number, since it uses as much as digits as its factorization.

1978462391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 653184, while the sum is 50.

The square root of 1978462391 is about 44479.9099706823. The cubic root of 1978462391 is about 1255.3821031927.

The spelling of 1978462391 in words is "one billion, nine hundred seventy-eight million, four hundred sixty-two thousand, three hundred ninety-one".