21155340 has 24 divisors (see below), whose sum is σ = 59235120. Its totient is φ = 5641408.

The previous prime is 21155339. The next prime is 21155363. The reversal of 21155340 is 4355112.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 176235 + ... + 176354.

It is an arithmetic number, because the mean of its divisors is an integer number (2468130).

Almost surely, 2^21155340 is an apocalyptic number.

21155340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21155340 is an abundant number, since it is smaller than the sum of its proper divisors (38079780).

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

21155340 is a wasteful number, since it uses less digits than its factorization.

21155340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 352601 (or 352599 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 21155340 is about 4599.4934503704. The cubic root of 21155340 is about 276.5710190168.

The spelling of 21155340 in words is "twenty-one million, one hundred fifty-five thousand, three hundred forty".