21254751 has 16 divisors (see below), whose sum is σ = 35987200. Its totient is φ = 12145464.

The previous prime is 21254729. The next prime is 21254789. The reversal of 21254751 is 15745212.

It is a de Polignac number, because none of the positive numbers 2^k-21254751 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21256751) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 56041 + ... + 56418.

It is an arithmetic number, because the mean of its divisors is an integer number (2249200).

Almost surely, 2^21254751 is an apocalyptic number.

21254751 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21254751 is a deficient number, since it is larger than the sum of its proper divisors (14732449).

21254751 is a wasteful number, since it uses less digits than its factorization.

21254751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112475 (or 112469 counting only the distinct ones).

The product of its digits is 2800, while the sum is 27.

The square root of 21254751 is about 4610.2875181489. The cubic root of 21254751 is about 277.0035535869.

Adding to 21254751 its reverse (15745212), we get a palindrome (36999963).

The spelling of 21254751 in words is "twenty-one million, two hundred fifty-four thousand, seven hundred fifty-one".