21091347 has 10 divisors (see below), whose sum is σ = 31506948. Its totient is φ = 14060844.

The previous prime is 21091333. The next prime is 21091351. The reversal of 21091347 is 74319012.

It is not a de Polignac number, because 21091347 - 2¹⁶ = 21025811 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21091347.

It is not an unprimeable number, because it can be changed into a prime (21091307) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 130113 + ... + 130274.

Almost surely, 2^21091347 is an apocalyptic number.

21091347 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21091347 is a deficient number, since it is larger than the sum of its proper divisors (10415601).

21091347 is an equidigital number, since it uses as much as digits as its factorization.

21091347 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 260399 (or 260390 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 21091347 is about 4592.5316547630. The cubic root of 21091347 is about 276.2918698779.

The spelling of 21091347 in words is "twenty-one million, ninety-one thousand, three hundred forty-seven".