21261430 has 32 divisors (see below), whose sum is σ = 40388544. Its totient is φ = 8042496.

The previous prime is 21261413. The next prime is 21261433. The reversal of 21261430 is 3416212.

It is a junction number, because it is equal to n+sod(n) for n = 21261398 and 21261407.

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 15 ways as a sum of consecutive naturals, for example, 21834 + ... + 22786.

It is an arithmetic number, because the mean of its divisors is an integer number (1262142).

Almost surely, 2^21261430 is an apocalyptic number.

21261430 is a deficient number, since it is larger than the sum of its proper divisors (19127114).

21261430 is a wasteful number, since it uses less digits than its factorization.

21261430 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1080.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 21261430 is about 4611.0118195468. The cubic root of 21261430 is about 277.0325653433.

Adding to 21261430 its reverse (3416212), we get a palindrome (24677642).

The spelling of 21261430 in words is "twenty-one million, two hundred sixty-one thousand, four hundred thirty".