21400747 has 2 divisors, whose sum is σ = 21400748. Its totient is φ = 21400746.

The previous prime is 21400723. The next prime is 21400751. The reversal of 21400747 is 74700412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21400747 - 2¹⁵ = 21367979 is a prime.

It is not a weakly prime, because it can be changed into another prime (21406747) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10700373 + 10700374.

It is an arithmetic number, because the mean of its divisors is an integer number (10700374).

Almost surely, 2^21400747 is an apocalyptic number.

21400747 is a deficient number, since it is larger than the sum of its proper divisors (1).

21400747 is an equidigital number, since it uses as much as digits as its factorization.

21400747 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1568, while the sum is 25.

The square root of 21400747 is about 4626.0941408493. The cubic root of 21400747 is about 277.6363402209.

The spelling of 21400747 in words is "twenty-one million, four hundred thousand, seven hundred forty-seven".