21261436 has 24 divisors (see below), whose sum is σ = 43514240. Its totient is φ = 8899632.

The previous prime is 21261433. The next prime is 21261463. The reversal of 21261436 is 63416212.

It is a self number, because there is not a number n which added to its sum of digits gives 21261436.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21261433) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7626 + ... + 10033.

Almost surely, 2^21261436 is an apocalyptic number.

It is an amenable number.

21261436 is an abundant number, since it is smaller than the sum of its proper divisors (22252804).

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

21261436 is a wasteful number, since it uses less digits than its factorization.

21261436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17713 (or 17711 counting only the distinct ones).

The product of its digits is 1728, while the sum is 25.

The square root of 21261436 is about 4611.0124701631. The cubic root of 21261436 is about 277.0325914030.

Adding to 21261436 its reverse (63416212), we get a palindrome (84677648).

The spelling of 21261436 in words is "twenty-one million, two hundred sixty-one thousand, four hundred thirty-six".