521678421 has 64 divisors (see below), whose sum is σ = 893952000. Its totient is φ = 297354240.

The previous prime is 521678411. The next prime is 521678453. The reversal of 521678421 is 124876125.

It is not a de Polignac number, because 521678421 - 2⁶ = 521678357 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521678401) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1088860 + ... + 1089338.

It is an arithmetic number, because the mean of its divisors is an integer number (13968000).

Almost surely, 2^521678421 is an apocalyptic number.

It is an amenable number.

521678421 is a deficient number, since it is larger than the sum of its proper divisors (372273579).

521678421 is a wasteful number, since it uses less digits than its factorization.

521678421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 711 (or 705 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 521678421 is about 22840.2806681529. The cubic root of 521678421 is about 805.0094110495.

The spelling of 521678421 in words is "five hundred twenty-one million, six hundred seventy-eight thousand, four hundred twenty-one".