21542340 has 48 divisors (see below), whose sum is σ = 60520320. Its totient is φ = 5725440.

The previous prime is 21542321. The next prime is 21542341. The reversal of 21542340 is 4324512.

It is not an unprimeable number, because it can be changed into a prime (21542341) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 33825 + ... + 34455.

It is an arithmetic number, because the mean of its divisors is an integer number (1260840).

Almost surely, 2^21542340 is an apocalyptic number.

21542340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21542340 is an abundant number, since it is smaller than the sum of its proper divisors (38977980).

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

21542340 is a wasteful number, since it uses less digits than its factorization.

21542340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1212 (or 1210 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 21542340 is about 4641.3726417947. The cubic root of 21542340 is about 278.2472999143.

Adding to 21542340 its reverse (4324512), we get a palindrome (25866852).

It can be divided in two parts, 21 and 542340, that added together give a triangular number (542361 = T₁₀₄₁).

The spelling of 21542340 in words is "twenty-one million, five hundred forty-two thousand, three hundred forty".