21423986 has 4 divisors (see below), whose sum is σ = 32135982. Its totient is φ = 10711992.

The previous prime is 21423979. The next prime is 21423989. The reversal of 21423986 is 68932412.

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., 19971961 + 1452025 = 4469^2 + 1205^2 .

It is a super-2 number, since 2×21423986² = 917974352256392, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21423989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5355995 + ... + 5355998.

Almost surely, 2^21423986 is an apocalyptic number.

21423986 is a deficient number, since it is larger than the sum of its proper divisors (10711996).

21423986 is a wasteful number, since it uses less digits than its factorization.

21423986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10711995.

The product of its digits is 20736, while the sum is 35.

The square root of 21423986 is about 4628.6051894712. The cubic root of 21423986 is about 277.7367986600.

The spelling of 21423986 in words is "twenty-one million, four hundred twenty-three thousand, nine hundred eighty-six".