21102357 has 4 divisors (see below), whose sum is σ = 28136480. Its totient is φ = 14068236.

The previous prime is 21102313. The next prime is 21102377. The reversal of 21102357 is 75320112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21102357 - 2⁸ = 21102101 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102307) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3517057 + ... + 3517062.

It is an arithmetic number, because the mean of its divisors is an integer number (7034120).

Almost surely, 2^21102357 is an apocalyptic number.

It is an amenable number.

21102357 is a deficient number, since it is larger than the sum of its proper divisors (7034123).

21102357 is an equidigital number, since it uses as much as digits as its factorization.

21102357 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7034122.

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 21102357 is about 4593.7301836307. The cubic root of 21102357 is about 276.3399376838.

Adding to 21102357 its reverse (75320112), we get a palindrome (96422469).

It can be divided in two parts, 21 and 102357, that added together give a triangular number (102378 = T₄₅₂).

The spelling of 21102357 in words is "twenty-one million, one hundred two thousand, three hundred fifty-seven".