21261044 has 24 divisors (see below), whose sum is σ = 42658560. Its totient is φ = 9082656.

The previous prime is 21261041. The next prime is 21261059. The reversal of 21261044 is 44016212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21261041) 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, 9242 + ... + 11310.

It is an arithmetic number, because the mean of its divisors is an integer number (1777440).

Almost surely, 2^21261044 is an apocalyptic number.

It is an amenable number.

21261044 is an abundant number, since it is smaller than the sum of its proper divisors (21397516).

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

21261044 is a wasteful number, since it uses less digits than its factorization.

21261044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2447 (or 2445 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 21261044 is about 4610.9699630338. The cubic root of 21261044 is about 277.0308888299.

Adding to 21261044 its reverse (44016212), we get a palindrome (65277256).

It can be divided in two parts, 212 and 61044, that multiplied together give a triangular number (12941328 = T₅₀₈₇).

The spelling of 21261044 in words is "twenty-one million, two hundred sixty-one thousand, forty-four".