21542372 has 6 divisors (see below), whose sum is σ = 37699158. Its totient is φ = 10771184.

The previous prime is 21542363. The next prime is 21542377. The reversal of 21542372 is 27324512.

It can be written as a sum of positive squares in only one way, i.e., 16048036 + 5494336 = 4006^2 + 2344^2 .

It is not an unprimeable number, because it can be changed into a prime (21542377) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2692793 + ... + 2692800.

It is an arithmetic number, because the mean of its divisors is an integer number (6283193).

Almost surely, 2^21542372 is an apocalyptic number.

It is an amenable number.

21542372 is a deficient number, since it is larger than the sum of its proper divisors (16156786).

21542372 is a wasteful number, since it uses less digits than its factorization.

21542372 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5385597 (or 5385595 counting only the distinct ones).

The product of its digits is 3360, while the sum is 26.

The square root of 21542372 is about 4641.3760890495. The cubic root of 21542372 is about 278.2474376881.

Adding to 21542372 its reverse (27324512), we get a palindrome (48866884).

The spelling of 21542372 in words is "twenty-one million, five hundred forty-two thousand, three hundred seventy-two".