21115506 has 8 divisors (see below), whose sum is σ = 42231024. Its totient is φ = 7038500.

The previous prime is 21115453. The next prime is 21115511. The reversal of 21115506 is 60551112.

It is a sphenic number, since it is the product of 3 distinct primes.

21115506 is an admirable number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1759620 + ... + 1759631.

It is an arithmetic number, because the mean of its divisors is an integer number (5278878).

Almost surely, 2^21115506 is an apocalyptic number.

21115506 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21115506 is a wasteful number, since it uses less digits than its factorization.

21115506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3519256.

The product of its (nonzero) digits is 300, while the sum is 21.

The square root of 21115506 is about 4595.1611506018. The cubic root of 21115506 is about 276.3973221014.

Adding to 21115506 its reverse (60551112), we get a palindrome (81666618).

The spelling of 21115506 in words is "twenty-one million, one hundred fifteen thousand, five hundred six".