21433778 has 4 divisors (see below), whose sum is σ = 32150670. Its totient is φ = 10716888.

The previous prime is 21433771. The next prime is 21433831. The reversal of 21433778 is 87733412.

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., 21409129 + 24649 = 4627^2 + 157^2 .

It is not an unprimeable number, because it can be changed into a prime (21433771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5358443 + ... + 5358446.

Almost surely, 2^21433778 is an apocalyptic number.

21433778 is a deficient number, since it is larger than the sum of its proper divisors (10716892).

21433778 is a wasteful number, since it uses less digits than its factorization.

21433778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10716891.

The product of its digits is 28224, while the sum is 35.

The square root of 21433778 is about 4629.6628386957. The cubic root of 21433778 is about 277.7791061388.

The spelling of 21433778 in words is "twenty-one million, four hundred thirty-three thousand, seven hundred seventy-eight".