21731430 has 32 divisors (see below), whose sum is σ = 59606784. Its totient is φ = 4967136.

The previous prime is 21731419. The next prime is 21731441. The reversal of 21731430 is 3413712.

It is an interprime number because it is at equal distance from previous prime (21731419) and next prime (21731441).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a junction number, because it is equal to n+sod(n) for n = 21731397 and 21731406.

It is a congruent number.

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, 51532 + ... + 51951.

It is an arithmetic number, because the mean of its divisors is an integer number (1862712).

Almost surely, 2^21731430 is an apocalyptic number.

21731430 is an abundant number, since it is smaller than the sum of its proper divisors (37875354).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21731430 is a wasteful number, since it uses less digits than its factorization.

21731430 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103500.

The product of its (nonzero) digits is 504, while the sum is 21.

The square root of 21731430 is about 4661.6981884288. The cubic root of 21731430 is about 279.0590437853.

The spelling of 21731430 in words is "twenty-one million, seven hundred thirty-one thousand, four hundred thirty".