21158040 has 32 divisors (see below), whose sum is σ = 63474480. Its totient is φ = 5642112.

The previous prime is 21158003. The next prime is 21158041. The reversal of 21158040 is 4085112.

It is a junction number, because it is equal to n+sod(n) for n = 21157998 and 21158016.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21158041) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 88039 + ... + 88278.

Almost surely, 2^21158040 is an apocalyptic number.

21158040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21158040 is an abundant number, since it is smaller than the sum of its proper divisors (42316440).

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

21158040 is a wasteful number, since it uses less digits than its factorization.

21158040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 176331 (or 176327 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 21158040 is about 4599.7869515881. The cubic root of 21158040 is about 276.5827845252.

The spelling of 21158040 in words is "twenty-one million, one hundred fifty-eight thousand, forty".