21078642 has 16 divisors (see below), whose sum is σ = 45400320. Its totient is φ = 6485712.

The previous prime is 21078637. The next prime is 21078703. The reversal of 21078642 is 24687012.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 135042 + ... + 135197.

It is an arithmetic number, because the mean of its divisors is an integer number (2837520).

Almost surely, 2^21078642 is an apocalyptic number.

21078642 is an abundant number, since it is smaller than the sum of its proper divisors (24321678).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21078642 is a wasteful number, since it uses less digits than its factorization.

21078642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270257.

The product of its (nonzero) digits is 5376, while the sum is 30.

The square root of 21078642 is about 4591.1482223949. The cubic root of 21078642 is about 276.2363811936.

The spelling of 21078642 in words is "twenty-one million, seventy-eight thousand, six hundred forty-two".