21421455 has 32 divisors (see below), whose sum is σ = 39363840. Its totient is φ = 9838080.

The previous prime is 21421453. The next prime is 21421489. The reversal of 21421455 is 55412412.

It is not a de Polignac number, because 21421455 - 2¹ = 21421453 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21421451) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 282 + ... + 6551.

It is an arithmetic number, because the mean of its divisors is an integer number (1230120).

Almost surely, 2^21421455 is an apocalyptic number.

21421455 is a deficient number, since it is larger than the sum of its proper divisors (17942385).

21421455 is a wasteful number, since it uses less digits than its factorization.

21421455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6871.

The product of its digits is 1600, while the sum is 24.

The square root of 21421455 is about 4628.3317728961. The cubic root of 21421455 is about 277.7258610826.

Adding to 21421455 its reverse (55412412), we get a palindrome (76833867).

The spelling of 21421455 in words is "twenty-one million, four hundred twenty-one thousand, four hundred fifty-five".