21356340 has 24 divisors (see below), whose sum is σ = 59797920. Its totient is φ = 5695008.

The previous prime is 21356339. The next prime is 21356341. The reversal of 21356340 is 4365312.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21356339) and next prime (21356341).

It is a self number, because there is not a number n which added to its sum of digits gives 21356340.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21356341) 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, 177910 + ... + 178029.

It is an arithmetic number, because the mean of its divisors is an integer number (2491580).

Almost surely, 2^21356340 is an apocalyptic number.

21356340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21356340 is an abundant number, since it is smaller than the sum of its proper divisors (38441580).

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

21356340 is a wasteful number, since it uses less digits than its factorization.

21356340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355951 (or 355949 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 24.

The square root of 21356340 is about 4621.2920271283. The cubic root of 21356340 is about 277.4441734950. Note that the first 3 decimals are identical.

The spelling of 21356340 in words is "twenty-one million, three hundred fifty-six thousand, three hundred forty".