21572501 has 2 divisors, whose sum is σ = 21572502. Its totient is φ = 21572500.

The previous prime is 21572479. The next prime is 21572503. The reversal of 21572501 is 10527512.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16728100 + 4844401 = 4090^2 + 2201^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21572501 is a prime.

Together with 21572503, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21572503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10786250 + 10786251.

It is an arithmetic number, because the mean of its divisors is an integer number (10786251).

Almost surely, 2^21572501 is an apocalyptic number.

It is an amenable number.

21572501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21572501 is an equidigital number, since it uses as much as digits as its factorization.

21572501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 700, while the sum is 23.

The square root of 21572501 is about 4644.6206518940. The cubic root of 21572501 is about 278.3770955209.

The spelling of 21572501 in words is "twenty-one million, five hundred seventy-two thousand, five hundred one".