21377540 has 12 divisors (see below), whose sum is σ = 44892876. Its totient is φ = 8551008.

The previous prime is 21377519. The next prime is 21377549. The reversal of 21377540 is 4577312.

It can be written as a sum of positive squares in 2 ways, for example, as 4468996 + 16908544 = 2114^2 + 4112^2 .

It is not an unprimeable number, because it can be changed into a prime (21377549) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 534419 + ... + 534458.

It is an arithmetic number, because the mean of its divisors is an integer number (3741073).

Almost surely, 2^21377540 is an apocalyptic number.

21377540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21377540 is an abundant number, since it is smaller than the sum of its proper divisors (23515336).

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

21377540 is a wasteful number, since it uses less digits than its factorization.

21377540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1068886 (or 1068884 counting only the distinct ones).

The product of its (nonzero) digits is 5880, while the sum is 29.

The square root of 21377540 is about 4623.5851890065. The cubic root of 21377540 is about 277.5359475115.

The spelling of 21377540 in words is "twenty-one million, three hundred seventy-seven thousand, five hundred forty".