21475399 has 16 divisors (see below), whose sum is σ = 25297920. Its totient is φ = 18024160.

The previous prime is 21475393. The next prime is 21475409. The reversal of 21475399 is 99357412.

It is not a de Polignac number, because 21475399 - 2⁵ = 21475367 is a prime.

It is a super-2 number, since 2×21475399² = 922385524418402, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21475393) 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, 5874 + ... + 8800.

It is an arithmetic number, because the mean of its divisors is an integer number (1581120).

Almost surely, 2^21475399 is an apocalyptic number.

21475399 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21475399 is a deficient number, since it is larger than the sum of its proper divisors (3822521).

21475399 is a wasteful number, since it uses less digits than its factorization.

21475399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2990.

The product of its digits is 68040, while the sum is 40.

The square root of 21475399 is about 4634.1556944065. The cubic root of 21475399 is about 277.9587908829.

The spelling of 21475399 in words is "twenty-one million, four hundred seventy-five thousand, three hundred ninety-nine".