21477391 has 16 divisors (see below), whose sum is σ = 24645600. Its totient is φ = 18551808.

The previous prime is 21477383. The next prime is 21477419. The reversal of 21477391 is 19377412.

It is a cyclic number.

It is not a de Polignac number, because 21477391 - 2³ = 21477383 is a prime.

It is a super-2 number, since 2×21477391² = 922556648333762, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21477301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21495 + ... + 22471.

It is an arithmetic number, because the mean of its divisors is an integer number (1540350).

Almost surely, 2^21477391 is an apocalyptic number.

21477391 is a deficient number, since it is larger than the sum of its proper divisors (3168209).

21477391 is a wasteful number, since it uses less digits than its factorization.

21477391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1098.

The product of its digits is 10584, while the sum is 34.

The square root of 21477391 is about 4634.3706153047. The cubic root of 21477391 is about 277.9673848527.

The spelling of 21477391 in words is "twenty-one million, four hundred seventy-seven thousand, three hundred ninety-one".