21628437 has 16 divisors (see below), whose sum is σ = 30664512. Its totient is φ = 13512960.

The previous prime is 21628429. The next prime is 21628447. The reversal of 21628437 is 73482612.

It is not a de Polignac number, because 21628437 - 2³ = 21628429 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21628398 and 21628407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21628417) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13362 + ... + 14892.

It is an arithmetic number, because the mean of its divisors is an integer number (1916532).

Almost surely, 2^21628437 is an apocalyptic number.

It is an amenable number.

21628437 is a deficient number, since it is larger than the sum of its proper divisors (9036075).

21628437 is a wasteful number, since it uses less digits than its factorization.

21628437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1828.

The product of its digits is 16128, while the sum is 33.

The square root of 21628437 is about 4650.6383432815. The cubic root of 21628437 is about 278.6174920352.

The spelling of 21628437 in words is "twenty-one million, six hundred twenty-eight thousand, four hundred thirty-seven".