21400553 has 4 divisors (see below), whose sum is σ = 21564048. Its totient is φ = 21237060.

The previous prime is 21400523. The next prime is 21400583. The reversal of 21400553 is 35500412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (21400523) and next prime (21400583).

It is a cyclic number.

It is not a de Polignac number, because 21400553 - 2¹⁸ = 21138409 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21400523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 81551 + ... + 81812.

It is an arithmetic number, because the mean of its divisors is an integer number (5391012).

Almost surely, 2^21400553 is an apocalyptic number.

It is an amenable number.

21400553 is a deficient number, since it is larger than the sum of its proper divisors (163495).

21400553 is a wasteful number, since it uses less digits than its factorization.

21400553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163494.

The product of its (nonzero) digits is 600, while the sum is 20.

The square root of 21400553 is about 4626.0731727892. The cubic root of 21400553 is about 277.6355012843.

Adding to 21400553 its reverse (35500412), we get a palindrome (56900965).

The spelling of 21400553 in words is "twenty-one million, four hundred thousand, five hundred fifty-three".