21426578 has 4 divisors (see below), whose sum is σ = 32139870. Its totient is φ = 10713288.

The previous prime is 21426553. The next prime is 21426583. The reversal of 21426578 is 87562412.

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., 12020089 + 9406489 = 3467^2 + 3067^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5356643 + ... + 5356646.

Almost surely, 2^21426578 is an apocalyptic number.

21426578 is a deficient number, since it is larger than the sum of its proper divisors (10713292).

21426578 is a wasteful number, since it uses less digits than its factorization.

21426578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10713291.

The product of its digits is 26880, while the sum is 35.

The square root of 21426578 is about 4628.8851789605. The cubic root of 21426578 is about 277.7479989529.

The spelling of 21426578 in words is "twenty-one million, four hundred twenty-six thousand, five hundred seventy-eight".