1978658421 has 16 divisors (see below), whose sum is σ = 2841722880. Its totient is φ = 1221050160.

The previous prime is 1978658419. The next prime is 1978658443. The reversal of 1978658421 is 1248568791.

It is not a de Polignac number, because 1978658421 - 2¹ = 1978658419 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1978658471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 460381 + ... + 464658.

It is an arithmetic number, because the mean of its divisors is an integer number (177607680).

Almost surely, 2^1978658421 is an apocalyptic number.

It is an amenable number.

1978658421 is a deficient number, since it is larger than the sum of its proper divisors (863064459).

1978658421 is a wasteful number, since it uses less digits than its factorization.

1978658421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 925096.

The product of its digits is 967680, while the sum is 51.

The square root of 1978658421 is about 44482.1134952016. The cubic root of 1978658421 is about 1255.4235637444.

The spelling of 1978658421 in words is "one billion, nine hundred seventy-eight million, six hundred fifty-eight thousand, four hundred twenty-one".