21403538 has 32 divisors (see below), whose sum is σ = 37410240. Its totient is φ = 9097920.

The previous prime is 21403483. The next prime is 21403559. The reversal of 21403538 is 83530412.

It is a super-2 number, since 2×21403538² = 916222877834888, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17693 + ... + 18863.

It is an arithmetic number, because the mean of its divisors is an integer number (1169070).

Almost surely, 2^21403538 is an apocalyptic number.

21403538 is a deficient number, since it is larger than the sum of its proper divisors (16006702).

21403538 is a wasteful number, since it uses less digits than its factorization.

21403538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1242.

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 21403538 is about 4626.3957893808. The cubic root of 21403538 is about 277.6484091040.

The spelling of 21403538 in words is "twenty-one million, four hundred three thousand, five hundred thirty-eight".