21545542 has 4 divisors (see below), whose sum is σ = 32318316. Its totient is φ = 10772770.

The previous prime is 21545509. The next prime is 21545551. The reversal of 21545542 is 24554512.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21545542.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5386384 + ... + 5386387.

It is an arithmetic number, because the mean of its divisors is an integer number (8079579).

Almost surely, 2^21545542 is an apocalyptic number.

21545542 is a deficient number, since it is larger than the sum of its proper divisors (10772774).

21545542 is a wasteful number, since it uses less digits than its factorization.

21545542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10772773.

The product of its digits is 8000, while the sum is 28.

The square root of 21545542 is about 4641.7175700381. The cubic root of 21545542 is about 278.2610852276.

The spelling of 21545542 in words is "twenty-one million, five hundred forty-five thousand, five hundred forty-two".