63978921 has 12 divisors (see below), whose sum is σ = 92895348. Its totient is φ = 42430464.

The previous prime is 63978919. The next prime is 63978953. The reversal of 63978921 is 12987936.

63978921 is a `hidden beast` number, since 639 + 7 + 8 + 9 + 2 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 6051600 + 57927321 = 2460^2 + 7611^2 .

It is not a de Polignac number, because 63978921 - 2¹ = 63978919 is a prime.

It is not an unprimeable number, because it can be changed into a prime (63978911) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16680 + ... + 20153.

It is an arithmetic number, because the mean of its divisors is an integer number (7741279).

Almost surely, 2^63978921 is an apocalyptic number.

It is an amenable number.

63978921 is a deficient number, since it is larger than the sum of its proper divisors (28916427).

63978921 is a wasteful number, since it uses less digits than its factorization.

63978921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37032 (or 37029 counting only the distinct ones).

The product of its digits is 163296, while the sum is 45.

The square root of 63978921 is about 7998.6824540045. The cubic root of 63978921 is about 399.9560805946.

The spelling of 63978921 in words is "sixty-three million, nine hundred seventy-eight thousand, nine hundred twenty-one".