21261456 has 90 divisors (see below), whose sum is σ = 62952630. Its totient is φ = 6697728.

The previous prime is 21261433. The next prime is 21261463. The reversal of 21261456 is 65416212.

It can be written as a sum of positive squares in only one way, i.e., 20793600 + 467856 = 4560^2 + 684^2 .

It is a super-2 number, since 2×21261456² = 904099022479872, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 51780 + ... + 52188.

Almost surely, 2^21261456 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21261456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31476315).

21261456 is an abundant number, since it is smaller than the sum of its proper divisors (41691174).

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

21261456 is a wasteful number, since it uses less digits than its factorization.

21261456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 461 (or 433 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 21261456 is about 4611.0146388837. The cubic root of 21261456 is about 277.0326782684.

Adding to 21261456 its reverse (65416212), we get a palindrome (86677668).

The spelling of 21261456 in words is "twenty-one million, two hundred sixty-one thousand, four hundred fifty-six".