421642978 has 4 divisors (see below), whose sum is σ = 632464470. Its totient is φ = 210821488.

The previous prime is 421642973. The next prime is 421642999. The reversal of 421642978 is 879246124.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 417262329 + 4380649 = 20427^2 + 2093^2 .

It is not an unprimeable number, because it can be changed into a prime (421642973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105410743 + ... + 105410746.

Almost surely, 2^421642978 is an apocalyptic number.

421642978 is a deficient number, since it is larger than the sum of its proper divisors (210821492).

421642978 is a wasteful number, since it uses less digits than its factorization.

421642978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210821491.

The product of its digits is 193536, while the sum is 43.

The square root of 421642978 is about 20533.9469659391. The cubic root of 421642978 is about 749.8624802675.

The spelling of 421642978 in words is "four hundred twenty-one million, six hundred forty-two thousand, nine hundred seventy-eight".