21090086 has 4 divisors (see below), whose sum is σ = 31635132. Its totient is φ = 10545042.

The previous prime is 21090073. The next prime is 21090101. The reversal of 21090086 is 68009012.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5272520 + ... + 5272523.

It is an arithmetic number, because the mean of its divisors is an integer number (7908783).

Almost surely, 2^21090086 is an apocalyptic number.

21090086 is a deficient number, since it is larger than the sum of its proper divisors (10545046).

21090086 is a wasteful number, since it uses less digits than its factorization.

21090086 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10545045.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 21090086 is about 4592.3943645989. The cubic root of 21090086 is about 276.2863634966.

Adding to 21090086 its reverse (68009012), we get a palindrome (89099098).

The spelling of 21090086 in words is "twenty-one million, ninety thousand, eighty-six".