21382551 has 12 divisors (see below), whose sum is σ = 30932928. Its totient is φ = 14233344.

The previous prime is 21382547. The next prime is 21382553. The reversal of 21382551 is 15528312.

It is a happy number.

It is not a de Polignac number, because 21382551 - 2² = 21382547 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21382553) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6391 + ... + 9143.

It is an arithmetic number, because the mean of its divisors is an integer number (2577744).

Almost surely, 2^21382551 is an apocalyptic number.

21382551 is a deficient number, since it is larger than the sum of its proper divisors (9550377).

21382551 is a wasteful number, since it uses less digits than its factorization.

21382551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3622 (or 3619 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 21382551 is about 4624.1270527528. The cubic root of 21382551 is about 277.5576310788.

The spelling of 21382551 in words is "twenty-one million, three hundred eighty-two thousand, five hundred fifty-one".