21628145 has 24 divisors (see below), whose sum is σ = 32609472. Its totient is φ = 13479840.

The previous prime is 21628141. The next prime is 21628147. The reversal of 21628145 is 54182612.

It is not a de Polignac number, because 21628145 - 2² = 21628141 is a prime.

It is a super-2 number, since 2×21628145² = 935553312282050, which contains 22 as substring.

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21628141) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1682 + ... + 6788.

It is an arithmetic number, because the mean of its divisors is an integer number (1358728).

Almost surely, 2^21628145 is an apocalyptic number.

It is an amenable number.

21628145 is a deficient number, since it is larger than the sum of its proper divisors (10981327).

21628145 is a wasteful number, since it uses less digits than its factorization.

21628145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5141 (or 5130 counting only the distinct ones).

The product of its digits is 3840, while the sum is 29.

The square root of 21628145 is about 4650.6069496357. The cubic root of 21628145 is about 278.6162381817.

The spelling of 21628145 in words is "twenty-one million, six hundred twenty-eight thousand, one hundred forty-five".