21261039 has 12 divisors (see below), whose sum is σ = 29636376. Its totient is φ = 13556752.

The previous prime is 21261029. The next prime is 21261041. The reversal of 21261039 is 93016212.

It is not a de Polignac number, because 21261039 - 2⁹ = 21260527 is a prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21261029) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5112 + ... + 8285.

It is an arithmetic number, because the mean of its divisors is an integer number (2469698).

Almost surely, 2^21261039 is an apocalyptic number.

21261039 is a deficient number, since it is larger than the sum of its proper divisors (8375337).

21261039 is a wasteful number, since it uses less digits than its factorization.

21261039 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13446 (or 13423 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 24.

The square root of 21261039 is about 4610.9694208485. The cubic root of 21261039 is about 277.0308671133.

The spelling of 21261039 in words is "twenty-one million, two hundred sixty-one thousand, thirty-nine".