21731045 has 8 divisors (see below), whose sum is σ = 29802624. Its totient is φ = 14901264.

The previous prime is 21731029. The next prime is 21731051. The reversal of 21731045 is 54013712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21731045 - 2⁴ = 21731029 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21731045.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 310409 + ... + 310478.

It is an arithmetic number, because the mean of its divisors is an integer number (3725328).

Almost surely, 2^21731045 is an apocalyptic number.

It is an amenable number.

21731045 is a deficient number, since it is larger than the sum of its proper divisors (8071579).

21731045 is an equidigital number, since it uses as much as digits as its factorization.

21731045 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 620899.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 21731045 is about 4661.6568942813. The cubic root of 21731045 is about 279.0573958133.

Adding to 21731045 its reverse (54013712), we get a palindrome (75744757).

The spelling of 21731045 in words is "twenty-one million, seven hundred thirty-one thousand, forty-five".