21263542 has 4 divisors (see below), whose sum is σ = 31895316. Its totient is φ = 10631770.

The previous prime is 21263537. The next prime is 21263579. The reversal of 21263542 is 24536212.

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

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, 5315884 + ... + 5315887.

It is an arithmetic number, because the mean of its divisors is an integer number (7973829).

Almost surely, 2^21263542 is an apocalyptic number.

21263542 is a deficient number, since it is larger than the sum of its proper divisors (10631774).

21263542 is a wasteful number, since it uses less digits than its factorization.

21263542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10631773.

The product of its digits is 2880, while the sum is 25.

The square root of 21263542 is about 4611.2408308394. The cubic root of 21263542 is about 277.0417380316.

Adding to 21263542 its reverse (24536212), we get a palindrome (45799754).

The spelling of 21263542 in words is "twenty-one million, two hundred sixty-three thousand, five hundred forty-two".