21621430 has 16 divisors (see below), whose sum is σ = 40967280. Its totient is φ = 8193312.

The previous prime is 21621427. The next prime is 21621437. The reversal of 21621430 is 3412612.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a junction number, because it is equal to n+sod(n) for n = 21621398 and 21621407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621437) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 56709 + ... + 57088.

It is an arithmetic number, because the mean of its divisors is an integer number (2560455).

Almost surely, 2^21621430 is an apocalyptic number.

21621430 is a deficient number, since it is larger than the sum of its proper divisors (19345850).

21621430 is a wasteful number, since it uses less digits than its factorization.

21621430 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113823.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 21621430 is about 4649.8849448132. The cubic root of 21621430 is about 278.5874007310.

The spelling of 21621430 in words is "twenty-one million, six hundred twenty-one thousand, four hundred thirty".