21266993 has 4 divisors (see below), whose sum is σ = 23200368. Its totient is φ = 19333620.

The previous prime is 21266977. The next prime is 21267011. The reversal of 21266993 is 39966212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21266993 - 2⁴ = 21266977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21266953) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 966671 + ... + 966692.

It is an arithmetic number, because the mean of its divisors is an integer number (5800092).

Almost surely, 2^21266993 is an apocalyptic number.

It is an amenable number.

21266993 is a deficient number, since it is larger than the sum of its proper divisors (1933375).

21266993 is a wasteful number, since it uses less digits than its factorization.

21266993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1933374.

The product of its digits is 34992, while the sum is 38.

The square root of 21266993 is about 4611.6150099504. The cubic root of 21266993 is about 277.0567248624.

It can be divided in two parts, 2126 and 6993, that added together give a palindrome (9119).

The spelling of 21266993 in words is "twenty-one million, two hundred sixty-six thousand, nine hundred ninety-three".