21388477 has 8 divisors (see below), whose sum is σ = 23681952. Its totient is φ = 19153200.

The previous prime is 21388469. The next prime is 21388517. The reversal of 21388477 is 77488312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21388477 - 2³ = 21388469 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21388417) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13774 + ... + 15247.

It is an arithmetic number, because the mean of its divisors is an integer number (2960244).

Almost surely, 2^21388477 is an apocalyptic number.

It is an amenable number.

21388477 is a deficient number, since it is larger than the sum of its proper divisors (2293475).

21388477 is a wasteful number, since it uses less digits than its factorization.

21388477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29099.

The product of its digits is 75264, while the sum is 40.

The square root of 21388477 is about 4624.7677779538. The cubic root of 21388477 is about 277.5832696567.

The spelling of 21388477 in words is "twenty-one million, three hundred eighty-eight thousand, four hundred seventy-seven".