21642093 has 16 divisors (see below), whose sum is σ = 34977600. Its totient is φ = 13116240.

The previous prime is 21642067. The next prime is 21642107. The reversal of 21642093 is 39024612.

21642093 = 282² + 283² + ... + 443².

It is not a de Polignac number, because 21642093 - 2¹² = 21637997 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21642013) 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, 36138 + ... + 36731.

It is an arithmetic number, because the mean of its divisors is an integer number (2186100).

Almost surely, 2^21642093 is an apocalyptic number.

It is an amenable number.

21642093 is a deficient number, since it is larger than the sum of its proper divisors (13335507).

21642093 is a wasteful number, since it uses less digits than its factorization.

21642093 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72889 (or 72883 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 21642093 is about 4652.1062971519. The cubic root of 21642093 is about 278.6761185551.

The spelling of 21642093 in words is "twenty-one million, six hundred forty-two thousand, ninety-three".