21474391 has 2 divisors, whose sum is σ = 21474392. Its totient is φ = 21474390.

The previous prime is 21474377. The next prime is 21474421. The reversal of 21474391 is 19347412.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21474391 is a prime.

It is a super-2 number, since 2×21474391² = 922298937641762, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21474361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10737195 + 10737196.

It is an arithmetic number, because the mean of its divisors is an integer number (10737196).

Almost surely, 2^21474391 is an apocalyptic number.

21474391 is a deficient number, since it is larger than the sum of its proper divisors (1).

21474391 is an equidigital number, since it uses as much as digits as its factorization.

21474391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6048, while the sum is 31.

The square root of 21474391 is about 4634.0469354550. The cubic root of 21474391 is about 277.9544419246.

The spelling of 21474391 in words is "twenty-one million, four hundred seventy-four thousand, three hundred ninety-one".