21891267 has 6 divisors (see below), whose sum is σ = 31620732. Its totient is φ = 14594172.

The previous prime is 21891227. The next prime is 21891269. The reversal of 21891267 is 76219812.

It is not a de Polignac number, because 21891267 - 2⁶ = 21891203 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21891269) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1216173 + ... + 1216190.

It is an arithmetic number, because the mean of its divisors is an integer number (5270122).

Almost surely, 2^21891267 is an apocalyptic number.

21891267 is a deficient number, since it is larger than the sum of its proper divisors (9729465).

21891267 is a wasteful number, since it uses less digits than its factorization.

21891267 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2432369 (or 2432366 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21891267 is about 4678.8104257386. The cubic root of 21891267 is about 279.7415429644.

The spelling of 21891267 in words is "twenty-one million, eight hundred ninety-one thousand, two hundred sixty-seven".