21369455 has 4 divisors (see below), whose sum is σ = 25643352. Its totient is φ = 17095560.

The previous prime is 21369451. The next prime is 21369473. The reversal of 21369455 is 55496312.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21369455 - 2² = 21369451 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21369451) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2136941 + ... + 2136950.

It is an arithmetic number, because the mean of its divisors is an integer number (6410838).

Almost surely, 2^21369455 is an apocalyptic number.

21369455 is a deficient number, since it is larger than the sum of its proper divisors (4273897).

21369455 is an equidigital number, since it uses as much as digits as its factorization.

21369455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4273896.

The product of its digits is 32400, while the sum is 35.

The square root of 21369455 is about 4622.7107848101. The cubic root of 21369455 is about 277.5009550058.

The spelling of 21369455 in words is "twenty-one million, three hundred sixty-nine thousand, four hundred fifty-five".